Inverted J-V Hysteresis in Perovskite Solar Cells: Insights from Photovoltaic Quantum Efficiency.

The most typical hysteresis in the current density-voltage (-) curve of perovskite solar cells (PSCs) shows better performance in the backward (BW) than in the forward (FW) voltage scan (normal hysteresis). The opposite, where the FW scan yields higher photocurrent, is known as inverted hysteresis and is also frequently observed. Here, we examine PSCs exhibiting both normal and inverted hysteresis, depending on scan rate and preconditioning. Spectral changes in the external quantum efficiency (EQE) linked to ionic redistribution reveal that inverted hysteresis arises from blue-range photocurrent losses caused by enhanced recombination at the interfaces due to ionic accumulation. This trend is consistent across PSC architectures, as demonstrated for triple mesoscopic carbon-based (C-PSCs) and planar p-i-n devices. Combined with drift-diffusion simulations, the results show that ionic losses can be bidirectional, and the hysteresis direction depends on how the ionic distribution impacts charge collection efficiency.