RESUMO
Efficiency reduction in perovskite solar cells (PSCs) during the magnification procedure significantly hampers commercialization. Vacuum-flash (VF) has emerged as a promising method to fabricate PSCs with consistent efficiency across scales. However, the slower solvent removal rate of VF compared to the anti-solvent method leads to perovskite films with buried defects. Thus, this work employs low-toxic Lewis base ligand solvent N-ethyl-2-pyrrolidone (NEP) to improve the nucleation process of perovskite films. NEP, with a mechanism similar to that of N-methyl-2-pyrrolidone in FA-based perovskite formation, enhances the solvent removal speed owing to its lower coordination ability. Based on this strategy, p-i-n PSCs with an optimized interface attain a power conversion efficiency (PCE) of 24.19% on an area of 0.08 cm2. The same nucleation process enables perovskite solar modules (PSMs) to achieve a certified PCE of 23.28% on an aperture area of 22.96 cm2, with a high geometric fill factor of 97%, ensuring nearly identical active area PCE (24%) in PSMs as in PSCs. This strategy highlights the potential of NEP as a ligand solvent choice for the commercialization of PSCs.
RESUMO
Reducing the interfacial defects between the perovskite/electron transport layer (ETL) is the key point to improving the efficient and stable performance of perovskite solar cells (PSCs). In this study, two self-assembled molecules ((aminomethyl)phosphonic acid and glycine) with different functional groups (phosphonic acid (-H2PO3) and carboxylic acid (-COOH)) were mixed to form the buried bottom interface of PSCs. The synergistic effect of -H2PO3 with its higher anchoring ability and -COOH with its fast carrier transport improved the performance of PSCs. Additionally, the SnO2 modified by mixed self-assembly molecules (M-SAM) showed a more appropriate energy level alignment, favoring charge transport and minimizing energy loss. In addition, the amine group (-NH2) on the two small molecules effectively interacted with uncoordinated Pb2+ in perovskite and improved the quality of the perovskite films. Consequently, the (FAPbI3)0.992(MAPbBr3)0.008 PSCs with M-SAM reached a PCE of 24.69% (0.08 cm2) and the perovskite modules achieved a champion efficiency of 18.57% (12.25 cm2 aperture area). Meanwhile, it still maintained more than 91% of its initial PCE after being placed in nitrogen atmosphere at 25 °C for 1500 h, which is better than that of the single-SAM and control devices. Further reference is provided for the future commercialization of perovskite with efficient and stable characteristics.
RESUMO
The main feature of perovskite solar cells (PSCs) is that the perovskite layer can be fabricated by the solution method, while the long-time stability of the precursor solution is critical. During the fabrication of formamidinium (FA)-based PSCs, the introduction of methylammonium cations (MA+) in the precursor solution can accelerate the crystallization process of the perovskite layer, stabilize the perovskite structure, and passivate defects. However, MA+ is easy to deprotonate to generate MA molecules, and it then condensates with formamidinium iodide (FAI) to form adverse byproducts. Herein, perovskite microcrystals (MCs) for preparing perovskite precursor solution were investigated in details, which can improve the long-term stability of the precursor solution and the perovskite film. We found that FA+ in MC solution was confined in the three-dimensional scaffold, preventing it from reacting with MA+. Meanwhile, MCs can effectively promote nucleation to form large grains in perovskite films. The photoelectric conversion efficiency (PCE) of the device with 3 week-aged MC solution remains at 90% and is only reduced by 10% after 160 h of continuous operation, which far exceeds the performance of the PCE of those based on mixed monomer powder (MP) solution. Therefore, perovskite MCs, an effective reactive inhibitor to improve the stability of perovskite precursor solutions, are of great significance for large-scale commercial fabrication.
