Fast Drying Boosted Performance Improvement of Low-Temperature Paintable Carbon-Based Perovskite Solar Cell

Low-temperature paintable carbon-based perovskite solar cells have been acknowledged as a promising photovoltaic device. However, the organometal trihalide perovskite film is always degraded by the solvents in the carbon paste, resulting in a fairly low efficiency. Unfortunately, in a conventional drying process, the movements of solvent molecules from a carbon paste to atmosphere are greatly obstructed by the biscale size of carbon black and graphite, which creates an extremely long evaporation path and drying time. To solve the problem, we have developed a simple, highly efficient and scalable method, a gas pump method (GPM), to dry the carbon paste very quickly which demonstrates a 7 times drying rate compared with conventional drying. As a result, the perovskite films covered by the carbon electrode (CE) dried by the GPM keep a uniform and continuous surface morphology, and the champion solar cell reveals a conversion efficiency of 12.30% with the area of 0.1 cm² and an open circuit voltage of 1.03 V, which are much higher than those (i.e., 4.73% and 0.81 V, respectively) observed for the PSC without GPM. Furthermore, the long-time stability test shows that the solar cells with the as-prepared CE retain more than 90% of its initial power conversion efficiency after 720 h.