Effective Interfaces between Fullerene Derivatives and CH₃NH₃PbI₃ to Improve Perovskite Solar Cell Performance

Abstract

Inverted hybrid perovskite solar cells using fullerene derivatives as an electron transport layer show high energy photoconversion efficiency and improvements in stability. In practice, a wide variety of fullerene derivative functional groups have been proposed, but there is still no clear understanding of the influence of this structure on solar cell behavior. Using density functional theory calculations, we study the conditions that allow the transport of electrons without energetic barriers in the interface formed between the surfaces of CH 3 NH 3 PbI 3 and the derivatives of fulleropyrrolidine and PCBM. Representative atomistic models of the interfaces are provided, and the self-consistent electronic structures obtained with hybrid functionals were analyzed. It is shown that only the perovskite surface terminated in a layer rich in methylammonium iodide offers electron transport without energy barriers for fullerene derivatives. Moreover, the lead iodide (PbI 2 )-terminated surface is not passivated with fullerene derivatives. The surface state disappears if the PbI 2 -terminated surface is treated with ammonium salts or zwitterionic compounds, such as methylammonium chloride and sulfamic acid. Therefore, these modified surfaces favor the performance of the solar cells if the interfaces remain aligned, without barriers, for the transport of electrons. Our study offers these interface models to contribute to the optimal design of perovskite solar cells.

Lead‐free perovskite Cs2NaGaBr6 n‐i‐p solar cell for higher power conversion efficiency to improved energy storage performance

“…According to the data presented in Figure 2B, It is evident that Cs2NaGaBr6 exhibits a superior quantum efficiency (99.2%) when compared to alternative lead‐based and lead‐free perovskite materials. Figure 2B (Inset) reflects the exact value of QE for respective lead‐based (CH 3 NH 3 PbI 3 ) 27 and lead‐free (CH 3 NH 3 SnBr 3 , FASnI 3 , and Cs 2 CuSbCl 6 ) perovskite materials 3,28,29 . Figure 2B also shows that CH 3 NH 3 PbI 3 base solar cells reflect quite higher QE than CH 3 NH 3 SnBr 3 , FASnI 3 , and Cs 2 CuSbCl 6 based solar cells but less than Cs 2 NaGaBr 6 based solar cell.…”