Synergistic Effect of Solvent and Component Engineering for High‐Efficiency Carbon‐Based Perovskite Solar Cells

It is highly desired to get rid of the high-temperature annealing process in manufacturing perovskite solar cells (PSCs) to reduce production costs. Herein, perovskite films are designed by rapidly evaporating of a mixture solvent consisting of methylamine ethanol solution (MA-EtOH sol) and acetonitrile (ACN) (MA-EtOH-ACN) by dopping different amounts of formamidinium iodide (FAI) into the CH3NH2PbI3 (MAPbI3) precursor solution; as a result, the high-temperature annealing step is effectively eliminated while the perovskite solar cell efficiency remains unchanged. The in situ UV-vis absorption for monitoring the perovskite crystallization process shows that FAI retards the crystallization rate, leading to a dense and smooth film. It is also found that the synergistic effect of solvent and composition engineering reduces defect density, boosts absorption strength, and enhances film stability. Consequently, high-performance ITO/SnO2/FA0.05MA0.95PbI3/carbon device is obtained with efficiency as high as 18.74%, with an excellent short circuit current of 25.04 mA cm-2, an open circuit voltage of 1.16 V, and a fill factor of 64.53%. The carbon-based perovskite solar cells also exhibit outstanding stability. This strategy offers a reference to producing efficient and stable perovskite cells by the straightforward ink method.