4-Hydrazinobenzoic-Acid Antioxidant for High-Efficiency Sn-Pb Alloyed Perovskite Solar Cells

Partial tin replacement of lead is expected to be an effective means to fine-tune the bandgap of Sn-Pb alloyed lead-halide perovskite to harvest near-infrared light and thus further increase the efficiency of solar cells based on it, in particular for use as a bottom component cell in the tandem cell design to break through the theoretical Shockley-Queisser (S-Q) limit of the single-junction solar cells. However, the efficiency of Sn-Pb alloyed perovskite solar cells (PSCs) is still lower than expected owing to the easy oxidation of Sn2+. Herein, a reducing agent 4-hydrazinobenzoic acid is developed as an additive to suppress the oxidation of Sn2+ and, meanwhile, passivate surface defects. It is found that the optoelectronic performance of Sn-Pb alloyed perovskites is improved as evidenced by the mitigated trap state density and suppressed nonradiative recombination. As a result, the Sn-Pb alloyed PSC efficiency is increased to 21.09%, one of the highest for cells with this bandgap. It is expected that this method is applicable for general Sn-Pb-based perovskite optoelectronics.

Automated summary

The addition of 4-hydrazinobenzoic acid as a reducing agent can suppress the oxidation of Sn2+ and passivate surface defects, leading to improved optoelectronic performance of Sn-Pb alloyed perovskites.