Additive-Assisted Defect Passivation for Minimization of Open-Circuit Voltage Loss and Improved Perovskite Solar Cell Performance

Abstract

Trap state formation in perovskite films during their preparation is a key limitation restricting the device performance and stability of perovskite solar cells. These trap states are generally present at the surface of perovskite films and on grain boundaries and work as charge recombination centers, thereby influencing the device performance. Hence, regulating these detrimental trap states that are susceptible to deformation is vital for improving the solar cell performance. Herein, a unique methodology of trap states passivation has been demonstrated using multiple carboxylic acid-functionalized small aromatic molecules. Three additives, viz., benzene carboxylic acid (BCA), benzene-1,3-dicarboxylic acid (BDCA), and benzene-1,3,5-tricarboxylic acid (BTCA), have been utilized as additives in the precursor solution that reduced trap states in the perovskite films. Perovskite films generated in the presence of these additives strongly influence the charge transfer dynamics and result in improved performance and stability of the devices by lowering the photogenerated charge recombination. BTCA-incorporated devices result in the highest power conversion efficiency (PCE) of 18.30% with a significant improvement in the open-circuit voltage (Voc) to 1075.9 mV (an enhancement of ≈80 mV) compared to the control device. Additionally, the devices also show enhanced thermal stability.