Preparation of low-cost perovskite solar cells with high-quality perovskite films in an ambient atmosphere

Abstract

High-quality perovskite films are extremely crucial to obtain perovskite solar cells with excellent photovoltaic performance, especially for carbon-based hole transport materials (HTM)-free perovskite solar cells. In this work, a facile and low-cost double two-step method (DT-method) is developed to prepare uniform and pinhole-free CH₃NH₃PbI₃perovskite films in an ambient atmosphere by utilizing the dissolution-recrystallization of PbI₂in DMF. That is to spin-coat PbI₂and CH₃NH₃I solution sequentially onto pristine perovskite films prepared by the conventional two-step method. The solar cells fabricated by the DT-method show a dramatic performance improvement, includingV_oc,J_sc, and fill factor reach 0.85 V, 15.56 mA cm^-2, and 0.58 respectively, which increase power conversion efficiency from 3.93% to 7.58% compared with the conventional two-step method. The improvement in performance and stability of solar cells is mainly due to the higher coverage of perovskite films onto the underlying mesoporous TiO₂layer and a negligible amount of PbI₂residue, which can effectively reduce charge recombination and promote the rapid transfer of charge carriers. In summary, this work presents a process for preparing carbon-based HTM-free perovskite solar cells (PSCs) in a high-humidity atmospheric environment (60%-85%). This simple device structure and preparation condition can greatly reduce the production threshold and cost of PSCs.

Keywords: carbon; high-quality perovskite films; low-cost; porous PbI2; stability.