Hot Carrier Cooling Mediated Efficiency Enhancement in Diamine Passivated Perovskite Solar Cells

Slowing hot carrier (HC) cooling in halide perovskites emerges as an efficient strategy to enhance the power conversion efficiency (PCE) of perovskite solar cells (PSCs). This approach facilitates the rapid extraction of HCs before they dissipate within the intricate lattice of the perovskite structure. In this investigation, we delve into the impact of amine-based additives on the relaxation of HCs in perovskite solar cells using a diamine 4,4′-diaminodiphenylmethaneiodide salt (MDA). The diamine has been used as an in situ additive in the perovskite precursor. The ultrafast femtosecond transient absorption (fs-TA) spectroscopy study confirms that the diamine-modified film slows the HC cooling time to 672 fs from the control (538 fs). Moreover, MDA additive helps to improve crystallization and passivate the traps for inhibiting nonradiative recombination, leading to higher PCE compared to the control device. The passivated devices show impressive ambient stability and retain 80% of initial PCE after 500 h. Our study provides an in-depth understanding of how precise control of HC cooling through additive engineering can improve the PSC’s efficiency and stability.