Anti-solvent free fabrication of FA-Based perovskite at low temperature towards to high performance flexible perovskite solar cells

Flexible solar cells have attracted increasingly attentions due to its possible extensive applications in wearable, portable, flyable and deployable devices. The fabrication of flexible perovskite solar cells (PSCs) strictly requires the fabrication temperature below 150 °C due to the limitation of flexible substrate. For retaining the process at low temperature, applying anti-solvents has becoming to the most popular method. However, the involvement of anti-solvents requires very precise control and brings toxicity in the fabrication procedures, which limits its large-scale industrial use. Here, we propose a strategy that simply replacing the usual anti-solvents with CH3NH3Br (CH3NH3+, MA) into dynamic spinning of perovskite precursor significantly reduces the formation energy of α-phase FA-perovskites to 40 °C. An optimized annealing temperature at 100 °C provides high-quality morphology and crystallization of FA-based perovskite films with superior optoelectric properties, yielding a power conversion efficiency (PCE) of flexible PSCs to 18.5% and retaining over 80% of its initial PCE after 1200 bending cycles. This is the best performance so far of preparing anti-solvent free flexible PSCs at low temperature (≤100 °C). Our results offer new insights into producing high-quality FA-based perovskite materials at low temperature, which paves the way for further development of flexible PSCs to industrial commercialization.