Stressing Halide Perovskites with Light and Electric Fields

Understanding the light and electric field-induced effects underlying the local changes in optoelectronic properties in lead halide perovskites is crucial to establish a detailed structure-function relationship. Here, we use single-molecule absorption scanning tunneling microscopy (SMA-STM) to probe the local surface inhomogeneity of a mixed A-site cation/mixed halide perovskite under pulsed 532 nm photoexcitation to gain insight into the varying grain-to-grain absorption behavior at the nanoscale and reduction in the electronic bandgap under illumination. To correlate the observed changes in the absorption signal to structural ones, we utilize synchrotron X-ray STM (SX-STM) where we find that photoexcitation induces changes in the X-ray absorption spectral signatures. Lastly, using pump-probe time-resolved wide-angle X-ray scattering, we show the presence of nonthermal lattice deformations upon photoexcitation which indicate that the excited photocarriers distort the perovskite lattice, corroborating the local electronic changes observed by our STM measurements.

Automated summary

Understanding the local changes in optoelectronic properties in lead halide perovskites under light and electric field-induced effects is crucial for establishing a detailed structure-function relationship. In this study, we used single-molecule absorption scanning tunneling microscopy (SMA-STM) to investigate the nanoscale surface inhomogeneity of a mixed A-site cation/mixed halide perovskite under pulsed 532 nm photoexcitation, which provided insights into the variation of grain-to-grain absorption behavior and reduction in electronic bandgap under illumination. By combining synchrotron X-ray STM (SX-STM) and pump-probe time-resolved wide-angle X-ray scattering, we further correlated the observed changes in absorption signals with structural changes and demonstrated the presence of nonthermal lattice deformations upon photoexcitation.