Large-area hysteresis-free perovskite solar cells via temperature controlled doctor blading under ambient environment

Hybrid perovskites have emerged as the most promising thin-film photovoltaic technology with efficiencies exceeding 20% merely in the last five years. Most high-efficiency perovskite solar cells reported in the recent years have relatively small device area in comparison to that required for commercial photovoltaic modules. While these results are excellent from an academic perspective, scaling up the overall cell device area is crucial for achieving practical utility for hybrid perovskite based thin-film solar cells. In this paper, we present a comprehensive study on the use of temperature-controlled doctor blading technique for the growth of large island, crystalline perovskite thin-films. Specifically, we elucidate the physical conditions such as substrate temperature, solution volume, and blade speed under ambient conditions that control the growth of large area perovskite thin-films with desired island size, thickness, uniformity and crystallinity. Using these doctor-bladed thin-films we fabricated devices of 1 cm2 area in air that yielded an average efficiency of 7.32% with negligible hysteresis in the current-voltage scans. Further improvements in efficiency can be expected by reproducing the perovskite thin-film growth using doctor-blading in a controlled environment, through compositional tuning of the band-gap, or by selecting electron and hole transport layers with better band alignment with the perovskite electronic energy level. Published by Elsevier Ltd.