How antisolvent miscibility affects perovskite film wrinkling and photovoltaic properties

Charge carriers' density, their lifetime, mobility, and the existence of trap states are strongly affected by the microscopic morphologies of perovskite films, and have a direct influence on the photovoltaic performance. Here, we report on micro-wrinkled perovskite layers to enhance photocarrier transport performances. By utilizing temperature-dependent miscibility of dimethyl sulfoxide with diethyl ether, the geometry of the microscopic wrinkles of the perovskite films are controlled. Wrinkling is pronounced as temperature of diethyl ether (T-DE) decreases due to the compressive stress relaxation of the thin rigid film-capped viscoelastic layer. Time-correlated single-photon counting reveals longer carrier lifetime at the hill sites than at the valley sites. The wrinkled morphology formed at T-DE=5 degrees C shows higher power conversion efficiency (PCE) and better stability than the flat one formed at T-DE=30 degrees C. Interfacial and additive engineering improve further PCE to 23.02%. This study provides important insight into correlation between lattice strain and carrier properties in perovskite photovoltaics. Perovskite morphology dictates carriers' behaviors and defect states, and thus the ultimate performance of the material. Here, the authors investigate micro-wrinkle formation in film by varying composition and deposition condition, and further implement the optimized structure for solar cells, achieving 23% efficiency.

Automated summary

The microscopic morphologies of perovskite films strongly influence the density, lifetime, mobility, and trap states of charge carriers, thus impacting the photovoltaic performance. By controlling the geometry of micro-wrinkles in perovskite layers, photocarrier transport performances can be enhanced. The study demonstrates that the wrinkled morphology formed at lower temperatures shows higher power conversion efficiency and better stability, with further improvement achieved through interfacial and additive engineering, reaching an efficiency of 23.02%.