English

• Carbon based all-inorganic CsPbBr₃ perovskite solar cells (PSCs) have attracted wide attention recently due to their low production cost and great intrinsic reliability [1-3]. However, their hole extraction and transport capabilities are far inferior to perovskite solar cells with a hole transport layer, leading to a significantly higher probability of charge recombination at the interface and thus lower power conversion efficiency (PCE) [4,5].

  CsPbBr₃ PSCs are predominantly structured with an electron transport layer, the active perovskite layer (CsPbBr₃), and a carbon electrode. PSCs prepared with CsPbBr₃, which is rich in Br, exhibit a reduction in open-circuit voltage of up to 0.6 V, while MAPbI₃ is only 0.3 V, resulting in a significant PCE loss. The efficient and stable performance of CsPbBr₃ PSC devices is affected by defects in the perovskite active layer, poor hole transport ability at the interface between the perovskite active layer and the carbon electrode, and the energy level difference between the layers. Therefore, it is important to optimize the perovskite active layer to address these issues and improve the efficiency of CsPbBr₃ PSCs. Recently, many electron-donating organic molecules containing -NH₂ groups have been demonstrated to passivate defects by forming coordination bonds with uncoordinated Pb²⁺ and Pb⁰ clusters on the surface of the perovskite layer, based on Lewis acid-base chemistry for lattice modulation to enhance efficiency and stability [6-8]. Recent studies have shown that the proton behavior induced by Lewis base-assisted passivation at the interface exerts a significant influence on the lattice structure of hybrid perovskite and the charge transfer kinetics in perovskite solar cells. Utilizing multifunctional organic molecules with -NH₂ groups to enhance the perovskite framework allows for the simultaneous modification of the crystallization process and effective passivation, resulting in a reduction of defect density. Furthermore, the interconnected organic framework contributes to the formation of a moisture-resistant layer on the perovskite surface [9-11]. The optimized mechanism mainly involves coordination reactions with surface dangling Pb²⁺ complex centers. This mechanism modulates the electronic states at the interface, leading to a corresponding alteration in the work function (WF) and valence band position of the perovskite film upon its integration into PSCs. Since the electron-donating ability and stability of surface-optimized molecules depend on specific interactions with the surface, the precise control of molecular structures will determine the overall performance of PSCs.

  In this work, amino-functionalized tetraphenylethene derivatives, tetra(4-aminophenyl)ethylene (TPE) and tetra(4-aminobiphenyl)ethylene (TPE-Ph), were used to optimize the interface between CsPbBr₃ and the carbon electrode. The results showed that when TPE and TPE-Ph were used to optimize the CsPbBr₃/carbon electrode interface, it was found that TPE and TPE-Ph, as strong electron-donating molecules, were beneficial for the hole transfer at the CsPbBr₃/carbon electrode interface [12-15]. They have four amino groups at their terminals that can be employed for the passivation of surface defects in the perovskite thin film, greatly increasing the passivation efficiency of the perovskite film defects and improving the stability of the perovskite film. Because the perovskite thin film inevitably exhibits a considerable density of defects and energy barriers that impede charge transfer, by optimizing the perovskite thin film using TPE and TPE-Ph, an internal electric field can be formed to enhance the separation and migration ability of charge carriers, thereby reducing the defects that are inherent to the perovskite film and minimizing the loss of open-circuit voltage [16-19]. These benefits help significantly enhance the power conversion efficiency (PCE) to 9.38% and improve the stability of CsPbBr₃ PSCs.

  TPEs and TPE-Ph are a class of conjugated macrocycles whose inherent aromaticity makes them an important component of functional supramolecular materials. In this work, TPE and TPE-Ph compounds were used to optimize CsPbBr₃ films as shown in Fig. 1a. TPE and TPE-Ph as Lewis bases, along with the conjugated benzene ring, enhance the electron-donating effect of the N atom in the structure. When the molecules were assembled onto the CsPbBr₃ surface, they interacted with Pb²⁺ to form a Pb-N bond with Pb²⁺ in the perovskite film due to the electron-donating effect of the amino group on the molecules [20,21]. Compared to TPE, TPE-Ph has more benzene rings, allowing more electrons in the electron-donating benzene ring to be transferred to the amino group, resulting in a stronger electronegativity of the N atom. Therefore, TPE-Ph is more likely to coordinate with the uncoordinated Pb²⁺ on the surface of CsPbBr₃ to form Lewis acid-base adducts [22]. The benzene ring of this compound transfers more electrons to the amino group as shown in the electrostatic potential distribution image in Fig. 1b. In other words, the amino group can be thought of as an electron-rich structure and therefore capable of interacting strongly with Pb²⁺. With its electron-rich structure, it can enhance the hole extraction at the CsPbBr₃/carbon electrode interface, thus improving the optoelectronic performance of CsPbBr₃ PSCs devices [23,24]. The hole extraction capability and optoelectronic performance will be discussed in detail in the following tests. Thus, this work offers insights into the optimization of perovskite solar cells and serves as a reference for the synthesis of materials with enhanced performance.

  Figure 1

  

  Figure 1.  (a) Structural diagrams of TPE and TPE-Ph. (b) Electrostatic potential distribution images of TPE and TPE-Ph, and schematic illustration of the optimized thin film.

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  The morphology of perovskite films play a crucial role in optoelectronic devices. In order to assess the potential changes in the surface morphology of the perovskite films resulting from optimization with TPE and TPE-Ph, top-view SEM morphological characterization tests were performed. As shown in Fig. 2a, the CsPbBr₃ film exhibits large voids before optimization, which can act as a severe charge complexation center in the CsPbBr₃ PSCs, increasing the defect density at the interface and leading to a degradation of device performance [25,26]. However, the TPE-optimized perovskite films show a significant reduction of voids and the films become denser after TPE-Ph optimization. The atomic force microscopy (AFM) tests in Figs. 2b and c further demonstrate that the surface roughness of the optimized film is reduced, indicating a smoother surface morphology. This suggests that the optimization process is beneficial in obtaining smooth and high quality perovskite films.

  Figure 2

  

  Figure 2.  CsPbBr₃ film before and after optimization with TPE and TPE-Ph. (a) SEM images, (b) AFM images, and (c) 3D AFM images.

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  X-ray diffraction (XRD) represents a valuable technique for the investigation of the crystal structure of perovskite films. By performing XRD tests on the perovskite film before and after optimization with TPE and TPE-Ph, the changes in the crystal structure of the perovskite film can be determined. The XRD results of the control and optimized perovskite films are presented in Fig. 3a. Both exhibit diffraction peaks characteristic of the CsPbBr₃ phase, including three main peaks near 14.69° (100), 21.08° (110) and 30.04° (200). No positional shifts or additional peaks were observed with the addition of TPE and TPE-Ph, indicating that the tetraphenylethylene derivatives used for optimization had no discernible impact on the crystal structure of the perovskite [27]. However, the diffraction peaks in the TPE and TPE-Ph optimized CsPbBr₃ films showed enhanced intensity compared to the unoptimized films. The results indicate that the optimized CsPbBr₃ films have higher crystallinity, which is consistent with the observation of SEM tests. This can be attributed to the reduction of grain boundaries in the optimized perovskite film, resulting in lower trap density [28]. These improvements contribute to the photovoltaic performance of CsPbBr₃ PSCs.

  Figure 3

  

  Figure 3.  (a) XRD spectra, (b) XPS spectra, (c) UV–vis spectra, and (d) Tauc plots of CsPbBr₃ films before and after addition of the optimized layer.

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  In order to evaluate the role of TPE-Ph in promoting the performance of CsPbBr₃ PSCs, the chemical modification of the surface of the perovskite films before and after optimization was further investigated by XPS spectroscopy. As shown in Fig. 3b, compared with the two characteristic peaks of 138.6 eV (Pb 4f_7/2) and 143.4 eV (Pb 4f_5/2) in the control group, the two characteristic peaks of the perovskite films optimized by TPE-Ph were shifted to 137.5 eV (Pb 4f_7/2) and 142.3 eV (Pb 4f_5/2) toward the position of the low binding energy due to the strong electron-donating effect of TPE-Ph, and the chemical modification of the surface of CsPbBr₃ PSCs was further investigated by XPS spectra. The electron-donating effect of TPE-Ph allows Pb²⁺ in the CsPbBr₃ film to gain electrons, which enhances the shielding effect and increases the density of the surrounding electron cloud. According to literature reports, the electron donor RNH₂ strongly interacts with uncoordinated Pb²⁺, which suggests that -NH₂ in TPE-Ph has an effective coordination relationship with Pb²⁺. And, as expected, as shown in the ultraviolet-visible absorption spectra (UV–vis) and the optical bandgap maps obtained from the UV–vis (Figs. 3c and d), the CsPbBr₃/TPE-Ph films show significantly increased absorption peak intensities compared to the control perovskite films, which exhibited little change in the bandgap (E_g) of the perovskite films, which is roughly E_g = 2.36 eV, indicating that the enhanced crystallinity and improved film quality of CsPbBr₃ facilitate greater photon absorption in the perovskite active layer and reduce charge recombination, thereby augmenting the photogenerated current output [29,30].

  In order to further examine the surface work function and energy band structure of the films before and after optimization, the energy band positions of the valence band maxima (E_VBM) of the perovskite films with CsPbBr₃ and CsPbBr₃/TPE-Ph structures were determined using ultraviolet photoelectron spectroscopy (UPS), which usually uses ultraviolet light as its excitation source, causing photoelectrons to be emitted from the surfaces of the tested films. Based on the results shown in Figs. S3a and c (Supporting information), the E_VBM of CsPbBr₃/TPE-Ph is calculated to be −5.56 eV, which is higher than that of the pristine perovskite (−5.63 eV), and will establish a type II cascade structure, which can readily extract photogenerated holes attributed to the insertion of the intermediate energy levels and block the electrons from being trapped at the grain boundaries [31]. Based on E_g = 2.36 eV before and after optimization, the conduction band minimum (E_CBM) of CsPbBr₃/TPE-Ph is −2.427 eV, which is much higher than that of the pristine perovskite, −4.074 eV, and thus effectively blocks the electron transfer. Based on these results, the charge transfer properties and energy band arrangement of the TPE-Ph tailored perovskite films are shown in Fig. S3b (Supporting information).

  Steady-state photoluminescence spectroscopy (PL) is a technique used to study charge carrier transport properties in semiconductors and molecular systems. PL measurements recorded the fluorescence intensity of CsPbBr₃ films deposited on glass substrates under 385 nm excitation (Fig. 4a). After optimization, the fluorescence intensity of the CsPbBr₃ film increased significantly. This indicates a higher number of electrons in the CsPbBr₃ films transitioning from the valence band (VB) to the conduction band (CB) after TPE and TPE-Ph optimization. Subsequently, the creation of holes in the VB leads to electron-hole complexation and the production of more photons with higher energies, resulting in stronger photoluminescence. Time-resolved photoluminescence (TRPL) measurements were performed to further evaluate the concentration of electron-hole pairs and their dynamics in CsPbBr₃ films before and after optimization. Typically, charge-carrier complexation is characterized by TRPL decay. The normalized TRPL spectra and exponential decay fitting curves are shown in Fig. 4b, and the detailed decay data are listed in Table S1 (Supporting information). The optimized CsPbBr₃ film exhibits a longer photoluminescence decay lifetime. This indicates that the charge carriers in the films have longer average lifetimes, resulting in more desirable photoluminescent properties and better film quality. This is consistent with the results and trends observed in the PL tests, in addition to the fact that the TPE-Ph optimized CsPbBr₃ films performed better than the TPEs. The decay lifetimes of the carriers in the CsPbBr₃ films are closely related to the crystallinity of the perovskite, as the decay process is influenced by the structure and morphology of the perovskite. The crystallinity in turn affects the structure and morphology. This is also consistent with the results and trends observed in the XRD and SEM tests, which further supports the conclusion that the quality of the optimized films is improved and defects are reduced, thus enhancing the photovoltaic performance of the CsPbBr₃ PSCs [32].

  Figure 4

  

  Figure 4.  (a) PL spectra before and after adding the optimization layer, (b) TRPL decay curves, (c) SCLC curves, (d) V_OC dependence on light intensity plots, (e) impedance plots in the dark state, (f) J-V characteristic curves in the dark state, (g) transient photovoltaic voltage (TPV) decay curves, and (h) transient photocurrent (TPC) decay curves.

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  In order to investigate the defect states of CsPbBr₃ PSCs before and after optimization, space charge limiting current (SCLC) analysis was performed to measure the electron trap density. When the bias voltage is low, the current increases linearly with the bias voltage, which is known as ohmic behavior. When the bias voltage exceeds a specific threshold, the trap state is completely filled and the increase in current becomes sharp and nonlinear. The bias voltage at the inflection point is recognized as the trap fill limit voltage (V_TFL). From the results in Fig. 4c, it can be seen that the V_TFL value of the film without optimization is 1.38 V, while after optimization in TPE and TPE-Ph, the V_TFL value decreases to 1.27 V and 1.10 V, respectively. The trap state density can be calculated using equation , the trap state density (n_trap) can be calculated from the V_TFL, where q is the elementary charge, ε₀ is the vacuum permittivity, and ε is the relative dielectric constant, L is the thickness of the CsPbBr₃, and the detailed results are listed in Table S2 (Supporting information) [33]. After optimization, the calculated n_trap decreased from 1.60 × 10¹⁶ cm^-3 in the control to 1.47 × 10¹⁶ cm^-3 and 1.27 × 10¹⁶ cm^-3. High defect densities denote charge buildup and poor charge transport at the interface. The significant reduction in defect density after optimization of the perovskite film with electron-donating TPE and TPE-Ph, especially with optimized TPE-Ph containing more benzene rings, and the reduction in the density of defect states after optimization led to an improvement in device performance.

  In order to further investigate the charge recombination mechanism of the devices, the J-V characteristics at different light intensities were measured in this study. the relationship between V_OC and light intensity is shown in Fig. 4d and was calculated by the following equation: , where I is the light intensity, n is the ideality factor, K is Boltzmann's constant, T is the temperature in Kelvin, and q is the charge constant. The TPE-Ph optimized device exhibits a smaller fitting slope of 1.59 KT/q compared to the control device with a slope of 1.91 KT/q. This indicates a reduction in trap-assisted complexation under open-circuit conditions, suggesting improved charge carrier transport in the optimized device [34].

  Electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the charge transfer efficiency and transport resistance, which reflect the charge transfer efficiency at the interface inside the solar cell and reveal the source of performance enhancement. The Nyquist plots and equivalent circuit diagrams of the EIS test results in the dark state are shown in Fig. 4e. The charge recombination resistance (R_rec) of the devices optimized with TPE and TPE-Ph is higher than that of the unoptimized devices. Among them, the device optimized with TPE-Ph exhibits the highest R_rec, indicating unfavorable charge compounding. This may be attributed to the stronger electron-donating effect of TPE-Ph, which facilitates hole transport at the interface and effectively suppresses interfacial charge compounding, resulting in a larger R_rec [35,36]. Fig. 4f shows the J-V curves of the devices before and after optimization from 1.0 V to −1.0 V in the dark. It is clear that the optimized devices exhibit lower leakage current densities compared to the unoptimized PSCs, which indicates a reduction in leakage current after optimization.

  In addition, the carrier decay was characterized by transient photovoltage (TPV) and transient photocurrent (TPC) measurements. As shown in Fig. 4g, in the TPV test, the CsPbBr₃ layer optimized with TPE-Ph exhibits enhanced separation efficiency of photogenerated charges, which makes it easier to transport photogenerated electrons and holes to the electrodes [37]. After TPE pH optimization, the TPV test of the device shows higher transient photovoltage values. As a result, the solar cell optimized with TPE-Ph has a longer charge complex lifetime of 3.29 µs compared to the unoptimized device with a charge complex lifetime of 0.78 µs. This suggests that charge-carrier transport in the target device is faster after TPE-Ph optimization due to the reduction of the defect density and the effective suppression of charge-carrier complexation [38]. In the TPC test of the TPE-Ph optimized device, the transient photocurrent exhibits a smaller value and a shorter charge extraction time. As shown in Fig. 4h, the decay time of the transient photocurrent decreases from 43 µs to 41 µs, which is related to the shorter charge extraction time at the interface in the optimized device.

  From the cross-sectional SEM image of the device shown in Fig. 5a, the device exhibits a multilayer structure consisting of a 25 nm SnO₂ layer, a 450 nm monolayer CsPbBr₃ light-absorbing layer, and a 10 µm carbon layer. The well-defined monolayer CsPbBr₃ light-absorbing layer consists of relatively large CsPbBr₃ particles and exhibits an extended longitudinal stacking to form a film morphology. This promotes not only light absorption and carrier generation in the CsPbBr₃ PSCs, but also charge transport under illumination, which inhibits charge complexation and enhances effective charge transfer [39,40]. Fig. 5b shows the J-V characteristics of CsPbBr₃ PSCs before and after optimization with TPE and TPE-Ph, and Table S3 (Supporting information) summarizes the photovoltaic properties. The results show that the optimization resulted in different degrees of parameter improvements for the CsPbBr₃ PSCs. In particular, the device with TPE-Ph optimized layer achieved a champion PCE of 9.38%, and the improvement was primarily attributed to the increase in V_OC (1.594 V) and FF (80.3%), which was significantly higher than that of the unoptimized PSCs (1.550 V for V_OC, 0.77% for FF, and 7.85% for PCE). The enhancement of V_OC and FF can be attributed to the TPE-Ph reduction of the trap state density at the interface between the optimized CsPbBr₃ perovskite film and the carbon electrode, which reduces the energy loss, facilitates the charge transfer, and reduces the non-radiative recombination at the interface, resulting in improved device performance [41].

  Figure 5

  

  Figure 5.  (a) Cross-sectional SEM image of the complete device after TPE-Ph optimization. (b) J-V curves of the devices before and after optimization with TPE and TPE-Ph. (c) J-V curves of the devices before and after TPE-Ph optimization in different scan directions. (d) Stable power output curves of the devices before and after TPE-Ph optimization. Statistical distribution of performance parameters before and after optimization: (e) V_OC and (f) FF. (g) Water contact angle images before and after optimization. (h) PCE degradation trend of the devices before and after TPE-Ph optimization during aging process.

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  Furthermore, in order to investigate the effect of the TPE-Ph molecules on the device hysteresis, the performance of the device with the introduction of the TPE-Ph-optimized layer was tested under both reverse and forward scans. As shown in Fig. 5c and Table S4 (Supporting information), the obtained results indicate a significant reduction of hysteresis in the optimized PSCs compared to the unoptimized PSCs. The hysteresis factor (HI) of the device was calculated using equation: , and the HI value of the optimized device was reduced from 0.07 to 0.009, indicating that the hysteresis was improved with the introduction of TPE-Ph. This enhancement can be ascribed to the reduction of defects and charge recombination in the optimized perovskite film, as well as faster charge transfer, which enhances effective charge transfer and improves device performance, highlighting the positive impact of TPE-Ph on the improved performance of CsPbBr₃ PSCs. Steady-state power output tests were performed on the devices before and after the maximum power point optimization to verify the PCE enhancement of the optimized devices [42]. As shown in Fig. 5d, compared with the unoptimized PSCs with a steady-state power output of 7.30% at a maximum power point voltage of 1.123 V and a current density of 6.51 mA/cm², the CsPbBr₃ PSCs optimized with TPE-Ph exhibited a higher steady-state power of 9.18% at a maximum power point voltage of 1.224 V and a current density of 7.50 mA/cm² output, which is consistent with the J-V measurements.

  In order to explore the effect of TPE-Ph molecular optimization on the reproducibility of the photovoltaic performance of CsPbBr₃ PSCs, 25 devices before and after TPE-Ph optimization were selected for photovoltaic performance testing and statistically analyzed (Figs. 5e and f). The experimental results show that the reproducibility of photovoltaic performance is improved to some extent after the optimization of TPE-Ph molecules. In particular, both V_OC and FF show a significant improvement trend in the experimental data of the 25 optimized devices, indicating a reduction of fluctuations and a convergence of performance values [43]. This indicates that the photovoltaic performance of PSCs can be substantially enhanced via optimization of TPE-Ph molecules. After optimization, the average V_OC increased by about 0.068 V compared to unoptimized with a small standard deviation. The average value of FF also showed significant improvement after optimization with a corresponding decrease in standard deviation. These findings suggest that incorporating TPE-Ph molecularly optimized layers represents an effective strategy for enhancing the photovoltaic performance of CsPbBr₃ PSCs, and that this approach demonstrates a high degree of reproducibility.

  The hydrophobicity of the perovskite films before and after the addition of the optimized layer was visually assessed by measuring the water contact angle. The results are shown in Fig. 5g, where the water contact angle increased significantly from 16.08° to 51.82° and 74.29° after optimization. This may be attributed to the hydrophobicity of the TPE and TPE-Ph molecules, which is influenced by the covalent bonding between the amino and aromatic groups, allowing water molecules to weakly bind to the surface and form a hydrophobic layer on the perovskite film [44]. Considering its nonlinear ring structure, it also exhibits high hydrophobicity in solution. In order to verify the long-term stability before and after the addition of the optimized layer, the changes in the performance of the unencapsulated CsPbBr₃ PSCs before and after the optimization were recorded periodically every two days at 35% humidity to assess the long-term stability after the optimization. The results are shown in Fig. 5h, where the TPE-Ph optimized device exhibited slower PCE reduction compared to the control, retaining 92% of the initial PCE after 30 days, while the control under the same conditions retained only 65% of the initial efficiency after 30 days. One of the reasons for the improved stability of the CsPbBr₃ PSCs is the reduction of defects in the optimized device, where TPE-Ph effectively passivated the interfacial defects of CsPbBr₃ PSCs and improved charge carrier transport, thus preventing device aging. In addition, the hydrophobic TPE-Ph molecules enhance the hydrophobicity of the CsPbBr₃ surface, which improves the stability of CsPbBr₃ PSCs [45].

  In summary, we have developed a CsPbBr₃/carbon interface contact optimization strategy by synthesizing TPE and TPE-Ph as interface optimization layers to enhance the PCE and stability of CsPbBr₃ PSCs. Combining SEM, AFM, XRD, PL, and TRPL results, we have found that the introduction of TPE-Ph into the CsPbBr₃/carbon interface improves the charge carrier pathways without interfering with the crystal structure. Therefore, we have achieved a device based on CsPbBr₃/TPE-Ph/carbon film with a PCE of 9.38%, which is higher than the 7.85% obtained with CsPbBr₃/carbon film alone. Further studies indicate that the incorporation of the TPE-Ph optimization layer reduces defects in CsPbBr₃ PSCs and enhances the charge carrier transport at the interface, resulting in improved optoelectronic performance and stability of CsPbBr₃ PSCs. Thus, this strategy provides a new approach for the development of high-performance CsPbBr₃ PSCs.

  Declaration of competing interest

  The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

  CRediT authorship contribution statement

  Sheng Tang: Investigation, Data curation. Mingyue Liao: Writing – original draft, Validation. Weihai Sun: Writing – review & editing. Jihuai Wu: Writing – review & editing, Resources, Funding acquisition. Jiamin Lu:. Yiming Xie: Writing – review & editing.

  Acknowledgments

  This work was supported by the National Natural Science Foundation of China, and the authors sincerely thank the National Natural Science Foundation of China (Nos. 22271106 and 52073286), Science Foundation of State Key Laboratory of Structural Chemistry (No. 20230027). The authors thank the testing service provided by the IACHQU.

  Supplementary materials

  Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2025.110838.

  
  
• 1. [1]

     S.S. Mali, J.V. Patil, C.K. Hong, Nano Today 33 (2020) 100880. doi: 10.1016/j.nantod.2020.100880

  2. [2]

     W. Xiang, W. Tress, Adv. Mater. 31 (2019) 28.

  3. [3]

     J. Ding, J. Duan, C. Guo, Q. Tang, J. Mater. Chem. A 6 (2018) 21999. doi: 10.1039/c8ta02522c

  4. [4]

     Y. Sun, W. Chen, Z. Sun, Chin. Chem. Lett. 33 (2022) 1772–1778. doi: 10.1016/j.cclet.2021.08.055

  5. [5]

     J. Liang, Y.B. Qi, Mater. Today Nano 16 (2021) 100143. doi: 10.1016/j.mtnano.2021.100143

  6. [6]

     W. Zhang, M. Yuan, L. Han, et al., ACS Appl. Energy Mater. 6 (2023) 7003. doi: 10.1021/acsaem.3c00549

  7. [7]

     J. Bisquert, Y. Qi, T. Ma, Y. Yan, ACS Energy Lett. 2 (2017) 520. doi: 10.1021/acsenergylett.7b00085

  8. [8]

     Y. Yu, P. Gao, Chin. Chem. Lett. 28 (2017) 1144–1152. doi: 10.1016/j.cclet.2017.04.020

  9. [9]

     C. Liu, L. Zhang, X. Zhou, et al., Adv. Funct. Mater. 29 (2019) 1807604. doi: 10.1002/adfm.201807604

  10. [10]

      X. Qi, J. Wang, F. Tan, et al., ACS Appl. Mater. Interfaces 13 (2021) 55349. doi: 10.1021/acsami.1c16290

  11. [11]

      H. Wang, J. Du, X. Li, et al., Chem. Eng. J. 450 (2022) 137990. doi: 10.1016/j.cej.2022.137990

  12. [12]

      J.Y. Kim, J.W. Lee, H.S. Jung, H. Shin, N.G. Park, Chem. Rev. 120 (2020) 7867. doi: 10.1021/acs.chemrev.0c00107

  13. [13]

      X. Yu, F. Wu, X. Sun, et al., Chin. Chem. Lett. 35 (2024) 109821. doi: 10.1016/j.cclet.2024.109821

  14. [14]

      J.P. Correa-Baena, M. Saliba, T. Buonassisi, et al., Science 358 (2017) 739. doi: 10.1126/science.aam6323

  15. [15]

      M. Lira-Cantu, Nature Energy 2 (2017) 17115. doi: 10.1038/nenergy.2017.115

  16. [16]

      X. Sun, D. Zhao, Z. Li, Chin. Chem. Lett. 29 (2018) 219–231. doi: 10.1016/j.cclet.2017.09.038

  17. [17]

      X.L. Xu, L.B. Xiao, J. Zhao, et al., Angew. Chem. Int. Ed. 59 (2020) 19974. doi: 10.1002/anie.202008494

  18. [18]

      C. Li, H. Li, Z. Zhu, et al., J. Power Sources 537 (2022) 231519. doi: 10.1016/j.jpowsour.2022.231519

  19. [19]

      Y.Y. Zhao, J.L. Duan, Y.D. Wang, X.Y. Yang, Q.W. Tang, Nano Energy 67 (2020) 104286. doi: 10.1016/j.nanoen.2019.104286

  20. [20]

      K. Zou, Q. Li, J. Fan, et al., ACS Mater. Lett. 4 (2022) 1101. doi: 10.1021/acsmaterialslett.2c00123

  21. [21]

      Y. Wu, C. Lu, F. Gao, et al., J. Mater. Chem. C 11 (2023) 4393. doi: 10.1039/d3tc00275f

  22. [22]

      S.Y. Abate, Z. Yang, S. Jha, et al., ACS Appl. Mater. Interfaces 15 (2023) 25495. doi: 10.1021/acsami.3c02571

  23. [23]

      J. Zhu, M. Tang, B. He, et al., J. Mater. Chem. A 8 (2020) 20987. doi: 10.1039/d0ta08675d

  24. [24]

      X. Gong, H. Li, R. Zhou, et al., ACS Appl. Mater. Interfaces 113 (2021) 41149. doi: 10.1021/acsami.1c07610

  25. [25]

      J. Ti, J. Zhu, B. He, et al., J. Mater. Chem. A 10 (2022) 6649. doi: 10.1039/d2ta00389a

  26. [26]

      S. Lan, W. Zheng, S. Yoon, et al., ACS Appl. Energy Mater. 5 (2022) 14901. doi: 10.1021/acsaem.2c02370

  27. [27]

      J. Liang, X. Han, J.H. Yang, et al., Adv. Mater. 31 (2019) 1903448. doi: 10.1002/adma.201903448

  28. [28]

      J.Y. Chun, B.G. Kim, J.Y. Kim, W. Jang, D.H. Wang, Carbon Energy 5 (2023) 350. doi: 10.1002/cey2.350

  29. [29]

      L.K. Ono, N.-G. Park, K. Zhu, W. Huang, Y. Qi, ACS Energy Lett. 2 (2017) 1749. doi: 10.1021/acsenergylett.7b00517

  30. [30]

      G. Zhang, K. Zhang, Q. Yin, et al., J. Am. Chem. Soc 139 (2017) 2387. doi: 10.1021/jacs.6b11991

  31. [31]

      P. Lopez-Varo, J.A. Jimenez-Tejada, M. Garcia-Rosell, et al., ACS Energy Lett. 2 (2017) 1450. doi: 10.1021/acsenergylett.7b00424

  32. [32]

      Y. Feng, Z. Que, S. Zhai, et al., Sol. RRL 7 (2023) 2300105. doi: 10.1002/solr.202300105

  33. [33]

      W. Zhao, Z. Yao, F. Yu, D. Yang, S. Liu, Adv. Sci. 5 (2018) 1700131. doi: 10.1002/advs.201700131

  34. [34]

      C. Yukta, R. D., D. Prochowicz, et al., ACS Appl. Mater. Interfaces 14 (2022) 850. doi: 10.1021/acsami.1c19546

  35. [35]

      S.W. Lee, S. Bae, D. Kim, H.S. Lee, Adv. Mater. 32 (2020) 2002202. doi: 10.1002/adma.202002202

  36. [36]

      J. Wang, L. Chen, Z. Qian, et al., J. Mater. Chem. A 8 (2020) 25336. doi: 10.1039/d0ta07663e

  37. [37]

      Y. Wang, Y. Li, Z. Gao, et al., ACS Appl. Mater. Interfaces 15 (2023) 53558. doi: 10.1021/acsami.3c13868

  38. [38]

      Z. Yi, X. Li, B. Xiao, et al., Chem. Eng. J. (2023) 469 143790. doi: 10.1016/j.cej.2023.143790

  39. [39]

      T. Kim, R. Younts, W. Lee, et al., J. Mater. Chem. A 5 (2017) 22170. doi: 10.1039/C7TA07535A

  40. [40]

      X. Sun, B. He, J. Zhu, et al., Chem. Eng. J. 412 (2021) 128727. doi: 10.1016/j.cej.2021.128727

  41. [41]

      Y. Li, Y. Guo, Z. Chen, et al., Energy Environ. Sci. 15 (2022) 855. doi: 10.1039/d1ee02977k

  42. [42]

      K.C. Tang, P. You, F. Yan, Sol. RRL 2 (2018) 1800075. doi: 10.1002/solr.201800075

  43. [43]

      A.N. Cho, N.G. Park, ChemSusChem 10 (2017) 3687. doi: 10.1002/cssc.201701095

  44. [44]

      Y. Gao, W. Xu, F. He, et al., Nano Res. 14 (2021) 2294. doi: 10.1007/s12274-020-3224-8

  45. [45]

      X. Liu, X. Tan, Z. Liu, et al., Nano Energy 56 (2019) 184. doi: 10.3390/coatings9030184

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  Figure 1  (a) Structural diagrams of TPE and TPE-Ph. (b) Electrostatic potential distribution images of TPE and TPE-Ph, and schematic illustration of the optimized thin film.

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  Figure 2  CsPbBr₃ film before and after optimization with TPE and TPE-Ph. (a) SEM images, (b) AFM images, and (c) 3D AFM images.

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  Figure 3  (a) XRD spectra, (b) XPS spectra, (c) UV–vis spectra, and (d) Tauc plots of CsPbBr₃ films before and after addition of the optimized layer.

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  Figure 4  (a) PL spectra before and after adding the optimization layer, (b) TRPL decay curves, (c) SCLC curves, (d) V_OC dependence on light intensity plots, (e) impedance plots in the dark state, (f) J-V characteristic curves in the dark state, (g) transient photovoltaic voltage (TPV) decay curves, and (h) transient photocurrent (TPC) decay curves.

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  Figure 5  (a) Cross-sectional SEM image of the complete device after TPE-Ph optimization. (b) J-V curves of the devices before and after optimization with TPE and TPE-Ph. (c) J-V curves of the devices before and after TPE-Ph optimization in different scan directions. (d) Stable power output curves of the devices before and after TPE-Ph optimization. Statistical distribution of performance parameters before and after optimization: (e) V_OC and (f) FF. (g) Water contact angle images before and after optimization. (h) PCE degradation trend of the devices before and after TPE-Ph optimization during aging process.

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