Metal halide perovskites hold good prospects for thermoelectric applications. Photoexcitation is manifested to effectively increase carrier density of perovskites, yet the severe carrier recombination due to the bipolar effect leads to the significant Seebeck voltage loss. Herein, we discover a remarkably photo-enhanced thermoelectric effect in FASnI₃ thin film by depositing an electron transport layer, delivering a 28-fold enhancement in thermoelectric power factor (PF). It is found that carrier recombination is greatly suppressed via directional regulation of photogenerated carrier transport, leading to a concurrent increase of electrical conductivity (σ) and Seebeck coefficient (S). Such a strategy is applicable to other compositional tin perovskite films with higher carrier and defect densities, which are however less pronounced owing to the inferior photocarriers and the restrained electron extraction. Nonetheless, we achieve a champion PF up to ∼342 μW m^–1 K^–2 in CsSnI₃ films by virtue of their outstanding σ that plays a decisive role in comparison to that of S.

中文翻译：

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用于增强热电的卤化锡钙钛矿中光生载流子的方向调节


金属卤化物钙钛矿在热电应用中具有良好的前景。光激发可以有效地提高钙钛矿的载流子密度，但双极效应导致的严重载流子复合导致了显着的塞贝克电压损失。在本文中，我们通过沉积电子传输层在 FASnI₃ 薄膜中发现了显著的光增强热电效应，使热电功率因数 （PF） 提高了 28 倍。研究发现，通过光生载流子传输的方向调节，载流子复合受到极大抑制，导致电导率 （σ） 和塞贝克系数 （S） 同时增加。这种策略适用于其他具有较高载流子和缺陷密度的组成锡钙钛矿薄膜，但由于光载流子较差和电子提取受限，这些薄膜不太明显。尽管如此，我们在 CsSnI₃ 薄膜中实现了高达 ∼342 μW m^–1 K^–2 的冠军 PF，凭借其出色的σ，与 S 相比起着决定性的作用。