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

Abstract 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 CH 3 NH 2 PbI 3 (MAPbI 3 ) 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/SnO 2 /FA 0.05 MA 0.95 PbI 3 /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.