Electronic band structure engineering of metal-halide perovskites (MHP) is at the heart of fundamental materials research and photovoltaic applications. However, reconfiguring the band structures in MHPs for optimized electronic properties remains challenging. Researchers at Wuhan University have reported a generic strategy for constructing near-edge states to improve carrier properties, leading to enhanced device performances.
The near-edge states are designed around the valence band edge using theoretical prediction and constructed through tailored material engineering. These states are experimentally revealed with activation energies of around 23 milli-electron volts by temperature-dependent time-resolved spectroscopy.
Such small activation energies enable prolonged carrier lifetime with efficient carrier transition dynamics and low non-radiative recombination losses, as corroborated by the millisecond lifetimes of microwave conductivity.
By constructing near-edge states in positive-intrinsic-negative inverted cells, the team achieved a champion efficiency of 25.4% (25.0% certified) for a 0.07-cm2 cell and 23.6% (22.7% certified) for a 1-cm2 cell.
The most stable encapsulated cell retained 90% of its initial efficiency after 1,100 hours of maximum power point tracking under one sun illumination (100 mW/cm2) at 65 °C in ambient air.
