Tuning Lattice Structure of Ferroelastic Twin-Domains Achieving Efficient Perovskite Solar Cells

The impact of the lattice structure on photoelectronic properties of metal halide perovskites (MHP) is widely acknowledged. However, the correlation between crystallography and photogenerated charge carriers remains unclear. Herein, we report on the discrepant ferroelastic response and photoelectronic properties under direct current (DC)-poling or alternating current (AC)-poling in methylammonium lead iodide (MAPbI₃) twin-domains. A preferred crystal orientation is established only under DC-poling, which leads to domain boundary evolution and enhanced light scattering. Continuous DC-poling leads to an irreversible lattice expansion of approximately 0.1%, resulting in an elevated light absorption of 10%. Consequently, under DC-poling the short-circuit current density and open-circuit voltage of the solar cell are elevated by 1.34 mA cm^–2 and 135 mV, respectively. The power conversion efficiency (PCE) of poling-enhanced solar cells has reached 23.12%, representing one of the highest PCEs of MAPbI₃. This work reveals that microscopic modulation of crystallographic structure profoundly impacts solar cell performance.