Linear photogalvanic effects (PGEs) in Janus monolayer In₂SSe with five different central regions, which are pure, S-vacancy, In-vacancy, SSe-vacancy and InIn-vacancy are investigated by the non-equilibrium Green's function technique combined with density functional theory. Janus monolayer In₂SSe is a kind of new two-dimensional (2D) indirect bandgap semiconductor that generates photoresponse in the absence of external bias voltage, showing potential applications in low power consumption photoelectronic devices. It is found that the photoresponse is related to the polarization angle in the form of cosine function. All the introduction of defects has enhanced the photocurrent, but the degree is different. The concentration and the position of vacancy defects also affect the photoresponse. Compared with other vacancy types, single In vacancy has the best performance because it has the highest photocurrent (29.80) and the largest ER (183.33) simultaneously. Our results indicate that appropriate vacancy defects can significantly enhance the photoresponse and ER. Janus monolayer In₂SSe is promising in photoelectric detection.

_{采用非平衡格林函数技术结合密度研究了具有五个不同中心区域的Janus单层In 2} SSe中的线性光电效应（PGEs），即纯、S-空位、In-空位、SSe-空位和In-空位泛函理论。Janus 单层 In ₂SSe是一种新型二维（2D）间接带隙半导体，在没有外部偏置电压的情况下产生光响应，在低功耗光电器件中显示出潜在应用。发现光响应以余弦函数的形式与偏振角有关。所有缺陷的引入都增强了光电流，但程度不同。空位缺陷的浓度和位置也会影响光响应。与其他空位类型相比，单个In空位具有最佳性能，因为它同时具有最高的光电流（29.80）和最大的ER（183.33）。我们的结果表明，适当的空位缺陷可以显着增强光响应和 ER。Janus 单层 In ₂SSe 在光电检测方面很有前景。