Oxygen vacancy defects at the surface and grain boundaries of tin dioxide (SnO₂), an electron transport layer (ETL) material for perovskite solar cells (PSCs), can induce non-radiative recombination, thereby limiting further improvements in device efficiency. This study proposes a low-cost and efficient strategy for modifying the ETL using acesulfame potassium (ACE-K). The results demonstrated that the C=O and S=O groups in ACE-K molecules interact with the undercoordinated Sn⁴⁺ on the SnO₂ surface, significantly passivating the oxygen vacancy defects in SnO₂. Electrical conductivity of the film increased from 4.60×10^-6 S·cm^-1 to 6.23×10^-6 S·cm^-1. Moreover, ACE-K modification improved roughness (from 20.6 nm to 14.0 nm) and wettability of the SnO₂ film, providing a better substrate for perovskite film growth. Consequently, the perovskite films grown on this optimized ETL enlarged grain sizes from 970.90 nm to 1071.20 nm and enhanced light absorption capability. Space-charge-limited current (SCLC) measurements revealed that the defect density decreased from 4.84×10¹⁶ cm^-3 to 3.83×10¹⁶ cm^-3, while electrochemical impedance spectroscopy (EIS) confirmed a significant suppression of non-radiative recombination during charge carrier transport. Ultimately, power conversion efficiency (PCE) of the PSCs improved from 19.27% to 21.60%. In addition, unpackaged ACE-K modified PSCs maintained 91.67% of initial PCE after 2160 h stored in N₂, showing excellent long term stability.

In recent years, Sb₂(S,Se)₃ has been considered a promising photovoltaic material due to its excellent photovoltaic properties. However, the highest reported photoelectric conversion efficiency (PCE) of Sb₂(S,Se)₃ solar cells still lags far behind its theoretical PCE limit, partly due to severe carrier recombination in Sb₂(S,Se)₃ films. In this study, a process additive, formamidinesulfinic acid (FSA), was introduced into the precursor solution of Sb₂(S,Se)₃ by hydrothermal deposition method. The additive FSA not only optimizes (211) and (221) orientations as well as Se/S atomic ratio of Sb₂(S,Se)₃ films, but also reduces Sb₂O₃ content of carrier recombination center in the films. The dark saturation current density (J₀) and recombination resistance (R_rec) values of the solar cell with FSA are 1.10×10⁻⁵ mA·cm⁻² and 3147 Ω·cm⁻², respectively, which are significantly better than those of reference device (5.17×10⁻⁵ mA·cm⁻² and 974.3 Ω·cm⁻²), indicating that the carrier recombination loss of Sb₂(S,Se)₃ solar cell is restricted. Under AM 1.5G, the mean values of open circuit voltage (V_OC), short circuit current density (J_SC), fill factor (FF), and PCE for the solar cell with FSA are 0.69 V, 18.46 mA·cm⁻², 63.60%, and 8.04%, respectively, showing significant improvement compared to reference device (0.67 V, 17.82 mA cm⁻², 62.27%, and 7.70%). The best device contributes the highest PCE of 8.21%, and this unpackaged device maintains 82.1% of its initial efficiency after a 120 d aging test in air.

The fabrication of large-area, high-efficiency perovskite solar cell module (PSM) represents a pivotal stage in the industrialization of perovskite solar cells (PSCs). Leveraging volatile solvents within perovskite precursors is a streamlined approach which offers distinct advantages in the industrialization trajectory of PSCs, but often exhibits accelerated crystallization kinetics, diminutive grain dimensions and elevated defect densities within the films, consequently compromising device efficiency and stability. This study devised a volatile solvent system comprising methylamine/acetonitrile (MA/ACN) for the production of MAPbI₃ perovskite solar cells/module. Incorporation of an optimal quantity of PbCl₂ into the perovskite precursor solution served to retard crystallization kinetics and passivate grain boundary imperfections. Notably, small-area device fabricated via this methodology demonstrated a peak photovoltaic conversion efficiency (PCE) of 21.21%, alongside enhanced operational stability. Furthermore, PSM engineered through this approach achieved a PCE of 18.89%. This study presents a novel paradigm for advancing the large-scale industrial manufacturing of PSCs.

Carbon-based perovskite solar cells (C-PSCs) have attracted significant interest for their advantages of high photoelectric conversion efficiency (PCE), long-term stability and low cost, showing superiority in commercialization of perovskite solar cells (PSCs). However, the promoting effect of PbTiO₃ modification and polarization treatment on C-PSCs photovoltaic performance by in-situ generation of PbTiO₃ on a dense electron transport layer of TiO₂ (c-TiO₂) is still unknow.. It was found that the PbTiO₃ formed after reaction for 30 s could effectively restrict the sharp increase in resistance of the electron transport layer, and substantially reduced the carrier accumulation at the interface to 29.7%, greatly improving the carrier separation ability. In addition, the carrier accumulation was further reduced to 6.78% through polarizing the c-TiO₂/PbTiO₃ layer, so that PSCs displayed 0.93 V of open circuit voltage (V_oc), 14.83 mA/cm² of short circuit current density (J_sc), 51.16% of fill factor (FF), and 7.11% of PCE. This work comprehensively reports the methods of PbTiO₃ modification and polarization treatment, proposes a research strategy to improve the performance of C-PSCs, reveals the intrinsic mechanism for optimizing carrier transport performance, and provides a way for developing high-efficiency, low-cost and long-life commercial PSCs.

Recently, perovskite solar cells have developed marvelously of which power conversion efficiency (PCE) achieved 26.1%, but the mechanical bending and environmental stability of flexible perovskite solar cells (F-PSCs) have remained major obstacles to their commercialization. In this study, the quality and crystallization of perovskite thin films were enhanced by adding agarose (AG). The interaction mechanism, PCE, mechanical bending and environmental stability of the assembled F-PSCs were investigated. It was found that the perovskite films modified by the optimal concentration of AG (3 mmol/L) exhibited denser and smoother morphology, higher crystallinity and absorbance, the lowest defect state density, and lower charge transfer resistance of 2191 Ω. Based on the optimal photoelectric properties, PCE increased from 15.17% to 17.30%. TiO₂ nanoparticles (0.75 mmol/L) were further introduced to form a synergistic interaction with AG (3 mmol/L), which provided a rigid backbone structure, and thus enhanced the mechanical and environmental stability of perovskite layers. After 1500 cycles of bending (3 mm in radius), the AG/TiO₂ co-modified F-PSCs maintained 84.73% of initial PCE, much higher than the blank device (9.32%). After 49 d in the air, the optimal F-PSCs still maintained 83.27% of initial PCE, superior than the blank device (62.21%). This work provides possibility for preparing highly efficient and stable F-PSCs.

Tin dioxide (SnO₂) is widely used in perovskite solar cell (PSC) as an electron transport material due to its high transmittance, high electron mobility, good UV stability, and low-temperature processing. However, SnO₂ electron transport layer prepared from commercial colloidal solution still faces some challenges such as easy agglomeration, defects, and energy level mismatch, limiting its performance and stability. This study improved the quality of SnO₂ films by introducing a polymer chitin nanofiber (1,2-dibenzoyloxyphenylchitin, DC) into the SnO₂ precursor solution, and systematically studied the effect of DC on the precursor solution, film and device performance. Experimental results showed that DC additive could effectively inhibit the agglomeration of SnO₂ nanoparticles, ensuring a more homogeneous dispersion in the precursor solution. The improved SnO₂ films had smaller roughness and could be better wetted by perovskite solution, which is beneficial to closer contact with the perovskite layer. Simultaneously, the oxygen vacancy defects in the SnO₂ films were effectively passivated, and the proportion of defects was reduced to 30%, further improving the quality of the films. Based on the improved energy level matching between the SnO₂ electron transport layer and the perovskite layer, the carrier extraction and transport performance was optimized. The performance of DC-modified PSC was significantly improved, and the photoelectric conversion efficiency of the optimal device reached 19.11%. This work not only overcomes the agglomeration problem of the SnO₂ electron transport layer during the preparation process, but also provides theoretical guidance and method for improving the performance of perovskite solar cells.

As renewable and sustainable clean energy, solar energy has the potential to address current energy shortage and reduce environmental pollution caused by fossil fuels consumption. In recent years, the third-generation thin-film solar cells, such as dye-sensitized solar cells (DSSCs) and perovskite solar cells (PSCs), have attracted widespread attention due to their low cost, abundant materials, and high photoelectric performance. However, these devices still face challenges in terms of charge transfer efficiency and operational stability for their commercialization. Two-dimensional (2D) MXene materials have emerged as promising candidates for improving the performance of thin-film solar cells due to their unique properties, including high specific surface area, rich surface functional groups, high conductivity, tunable work function, and hydrophilicity. This review summarizes the recent research progress of 2D MXene materials applied in new thin-film solar cells, focusing on the reaction mechanism that enhances the photoelectric performance of solar cells. Strategies such as using 2D MXene materials as additives for the perovskite layer and charge transport layer in PSCs, modifying the photoanode in DSSCs, and preparing varous electrodes, can effectively improve light absorption efficiency, carrier mobility, and charge extraction capability of the devices by adjusting band alignment, reducing work function, broadening the light absorption range, and creating a “pillar support effect”. As a result, the photoelectric performance and stability of the devices are enhanced. In conclusion, the perspectives highlights the current research progress and challenge faced by 2D MXene materials in novel thin-film solar cells.

Recently, organic-inorganic hybrid perovskite solar cells have demonstrated a broad commercial prospect due to their high photoelectric conversion efficiency (PCE) and low fabricating costs. During the past decades, the highest reported PCE of small-area (<1 cm²) perovskite solar cells (PSCs) rose to 26.10%, and those of large-area (1-10 cm²), mini-module level (10-800 cm²) and module level (>800 cm²) PSCs increased to 24.35%, 22.40% and 18.60%, respectively. The performance of PSCs decreases dramatically with the area increasing due to limitation of the deposition method and the poor quality of large-area perovskite films. Spin-coating method is not suitable for actual industrial production, while the scalable deposition methods including blade-coating and slot-die coating still face the difficulty of precisely controlling nucleation and crystallization of the perovskite films with large area. This review summarized preparation methods of large-area perovskite films, and discussed the film-forming mechanism and strategies for high-quality perovskite films. Finally, relevant outlooks on technologies and applications for large-area PSCs with high performances and stabilities were analyzed. This review is expected to provide insights on the research of large-area PSCs with high performance.

Hysteresis effect greatly impacted performance and stability of perovskite solar cells. Ion migration and the resulting accumulation of interface ions were widely recognized as the most important origins. In this study, upconversion luminescent nanoparticles (UCNP) were used to modify the interface of the electron transport layer/perovskite active layer and the intrinsic perovskite active layer, and the effects of UCNP on the morphology, structure, spectral/optoelectronic properties, and ion migration kinetics of perovskite were systematically explored. The results indicated that the device with UCNP modified perovskite active layer has the best photoelectric conversion efficiency (PCE, 16.27%) and significantly improves the hysteresis factor (HF, 0.05). Furthermore, circuit switching transient optoelectronic technology was employed to investigate the ion migration kinetics without interference from photo-generated carriers, revealing the dual role of UCNP in suppressing ion migration and accumulation during the optoelectronic conversion process of perovskite solar cells. On the one hand, UCNP formed barrier layers that hinder ion accumulation. On the other hand, UCNP infiltrated into grain boundaries of perovskite phase during annealing, hindering ion migration and reducing the recovery voltage from 0.43 V to 0.28 V. The mechanism of carriers and ions interaction was explained based on the polarization-induced trap state model to declare the process of UCNP suppressing the hysteresis of perovskite photovoltaic devices. This work provides effective solution for regulating the hysteresis of perovskite solar cells.

In the preparation of Sn-Pb alloyed perovskite, a large amount of stannous fluoride (SnF₂) additive is often employed to inhibit the oxidation of Sn²⁺ ions. However, excessive SnF₂ deteriorates quality of the film, photoelectric conversion efficiency (PCE) and stability of the device. Therefore, the development of new antioxidants at low doses is essential to achieve high-performance Sn-Pb alloyed perovskite solar cells. In this study, a two-step process was used to prepare Sn-Pb alloyed perovskite film. In the first step, low-dose stannous iso-octanoate (SnOct₂) was introduced to replace SnF₂ to inhibit the oxidation of Sn²⁺. This study showed that the additive could improve the crystallization quality of the film, and the average grain size of the film with SnOct₂ could reach 850 nm while the amount of grain boundaries was reduced. The film with the addition of SnOct₂ still contained 93.5% Sn²⁺ after storage for 7 d in the glove box. And due to the excellent oxidation resistance of SnOct₂, the device with the additional SnOct₂ had a lower defect state density, which was reduced from 7.20×10¹⁵ to 4.74×10¹⁵ cm^-3, inhibiting the non-radiative recombination. In addition, SnOct₂ improved the surface energy levels of perovskite films. Finally, PCE of Sn-Pb alloyed perovskite cell supplemented with 0.030 mmol SnOct₂ reached 17.25%, superior to that of device supplemented with 0.10 mmol SnF₂ (11.63%). After storage in nitrogen for 50 d, more than 70% of initial PCE was still preserved.

Significant progress has recently been made in enhancing the power conversion efficiency (PCE) of perovskite solar cells (PSCs). The electron transport layer (ETL), as an essential component of PSCs, significantly influences the performance of devices. Traditional spin-coating method for preparing the ETL fails to fully cover the cusp of FTO transparent conductive glass substrate, leading to direct contact between perovskite film and FTO substrate, which induces charge recombination and reduces the performance of PSCs. To address this issue, an in-situ growth method was proposed to prepare conformal SnO₂ films on FTO glass substrates in this study. The resulting SnO₂ films are not only dense and uniform, fully covering the cusp of the FTO glass substrates and reducing the contact area between the FTO substrates and the perovskite films, but also facilitating the formation of perovskite films with large grain sizes. Moreover, the conformal SnO₂ films can improve the charge extraction at the SnO₂/perovskite interface, reduce the trap density and trap-assisted recombination in PSCs, and thus enhance the PCE of PSCs. Through comparative experiments, it is found that the PSCs with in-situ grown SnO₂ films show an improved PCE of 21.97%, which significantly increased compared to that with spin-coated SnO₂ films (20.93%). All above data demonstrate that the as-prepared SnO₂ film can serve as an ideal ETL. It is worth mentioning that this method avoids the use of corrosive hydrochloric acid and toxic thioglycolic acid, and it can also be extended to ITO flexible transparent conductive substrates in the future.