Compression and tensile strain based on piezo-phototronic effect represent a valid method for modulating the photocurrent of photodetectors. However, the underlying mechanism responsible for the asymmetric increase/decrease of photocurrent under identical compressive/tensile stresses remains unclear. Herein, a PVDF/CsPbBr composite fiber incorporating orthorhombic CsPbBr (a piezoelectric phase) is fabricated through room-temperature electrospinning. Subsequently, flexible photodetectors (PDs) based on PVDF/CsPbBr are constructed to explore the impact of strain on photocurrent. The results reveal a 103% increase in photocurrent under a strain of −0.09% (compressive strain), significantly exceeding the 38% decrease observed under a strain of 0.09% (tensile strain). Furthermore, the piezoelectric and ferroelectric properties of the orthorhombic CsPbBr are computed using density functional theory (DFT), confirming that the asymmetric modulation of photocurrent stems from the nature of the piezoelectric effect and ferroelectric effect. Additionally, the ferroelectric effect exerts a more pronounced influence on the photocurrent, which is 2.2 times greater than the piezoelectric effect. This work provides compelling evidence for the piezoelectric and ferroelectric effects of inorganic halide perovskites, underscoring the substantial potential of these effects in optoelectronic devices.

中文翻译：

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揭示压电和铁电效应对无机卤化物钙钛矿光电探测器的贡献

基于压电光电子效应的压缩和拉伸应变代表了调制光电探测器光电流的有效方法。然而，在相同的压/拉应力下光电流不对称增加/减少的潜在机制仍不清楚。在此，通过室温静电纺丝制备了包含正交晶系 CsPbBr（压电相）的 PVDF/CsPbBr 复合纤维。随后，构建了基于PVDF/CsPbBr的柔性光电探测器（PD），以探索应变对光电流的影响。结果表明，在-0.09% 的应变（压缩应变）下，光电流增加了 103%，明显超过在 0.09% 的应变（拉伸应变）下观察到的 38% 的下降。此外，利用密度泛函理论（DFT）计算了正交晶系CsPbBr的压电和铁电性质，证实光电流的不对称调制源于压电效应和铁电效应的本质。此外，铁电效应对光电流的影响更为明显，是压电效应的2.2倍。这项工作为无机卤化物钙钛矿的压电和铁电效应提供了令人信服的证据，强调了这些效应在光电器件中的巨大潜力。