A Fast Deposition‐Crystallization Procedure for Highly Efficient Lead Iodide Perovskite Thin‐Film Solar Cells

TLDR

Thin‑film photovoltaics based on alkylammonium lead iodide perovskite absorbers are a promising low‑cost solar technology, yet their layers are usually fabricated by vapor deposition or a two‑step sequential process. The study demonstrates that flat, uniform perovskite thin films can be produced by a one‑step, solvent‑induced fast crystallization method. The method uses spin‑coating of a DMF solution of CH₃NH₃PbI₃, then immediate chlorobenzene exposure to trigger crystallization. The resulting films contain micron‑sized crystalline grains, and planar heterojunction cells achieve an average power conversion efficiency of 13.9 % (±0.7 %) and a steady‑state efficiency of 13 % under AM 1.5.

Abstract

Abstract Thin‐film photovoltaics based on alkylammonium lead iodide perovskite light absorbers have recently emerged as a promising low‐cost solar energy harvesting technology. To date, the perovskite layer in these efficient solar cells has generally been fabricated by either vapor deposition or a two‐step sequential deposition process. We report that flat, uniform thin films of this material can be deposited by a one‐step, solvent‐induced, fast crystallization method involving spin‐coating of a DMF solution of CH 3 NH 3 PbI 3 followed immediately by exposure to chlorobenzene to induce crystallization. Analysis of the devices and films revealed that the perovskite films consist of large crystalline grains with sizes up to microns. Planar heterojunction solar cells constructed with these solution‐processed thin films yielded an average power conversion efficiency of 13.9±0.7 % and a steady state efficiency of 13 % under standard AM 1.5 conditions.