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Impact of Interface Energy Alignment on the Dynamic Current–Voltage Response of Perovskite Solar Cells

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journal contribution
posted on 2020-06-05, 15:36 authored by Zhe Sun, Yanan Kang, Guoguo Wang, Mao Liang, Song Xue
The mismatch of the energy level between the electron transport layer (ETL) and the perovskite (PS) film is one of the origins of current–voltage (JV) hysteresis in perovskite solar cells (PSCs). Drift-diffusion simulations are conducted to explain how the band alignment affects the charge extraction across the ETL/PS interface, and hence varies the responses of photocurrent. Our simulations show that the band alignment has a profound influence on the evolution of the profiles of movable ions during voltage scan. The band mismatch at the ETL/PS interface is shown to engender the accumulation of movable anions and give rise to severe JV hysteresis. We further demonstrate that a rational design on the energy alignment of PSCs is vital to reduce the hysteresis no matter if charge loss in PSCs is determined by bulk recombination or trap-assisted surface recombination. Moreover, the PSCs suffering from interface band mismatch are found to exhibit various hysteresis behaviors depending on the rate of voltage scan. It implies that the voltage scan at different speeds could be helpful to diagnose the problem of PSCs.

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