Preparation of high-performance quasi-two-dimensional (Q-2D) perovskite solar cells by fluorinated benzylamine groups at different substitution positions

Abstract

Quasi-two-dimensional (Q-2D) perovskite solar cells have garnered significant attention due to their unique hydrophobic organic cations and commendable stability. However, there is currently no established set of criteria for selecting the appropriate organic cations to fabricate highly efficient and stable Q-2D perovskite solar cells. This work systematically examines the organic interstitial cations containing fluorine atoms at various substitution positions in phenylmethylamine, focusing on crystal orientation, film morphology, and the photoelectric conversion efficiency (PCE) of n = 5 perovskite films. Through density functional theory (DFT) calculations and crystal structure analysis, it is revealed that compared to PMA-F, oFPMA-F and mFPMA-F, pFPMA-F exhibits the largest dipole moment. Additionally, (pFPMA)₂PbI₄ demonstrates a larger effective mass and greater layer spacing compared to (PMA)₂PbI₄. The findings revealed that in comparison to PMA-F, oFPMA-F and mFPMA-F, the pFPMA-F 2D perovskite film exhibits a preferential in-plane orientation, superior crystallinity, and higher carrier mobility. Consequently, the Q-2D perovskite solar cell device utilizing pFPMA-F achieved a PCE of 15.88%, which markedly surpassed those of the PMA-F (9.15%), oFPMA-F (12.62%), and mFPMA-F (7.8%) counterparts. Additionally, the device architecture based on pFPMA-F demonstrated exceptional stability.