Recently, all-inorganic two-dimensional (2D) Ruddlesden-Popper (RP) halide perovskites have drawn much attention due to their excellent stability in ambient air. However, their electronic and optical performance resulting from a wide bandgap and low carrier mobility have hindered their use in photodetectors. To overcome these limitations, in this work, taking advantage of hexagonal indium selenide ($\mathrm{In}\mathrm{Se}$) with a high electron mobility, we construct an atomically thin heterostructure. Density-functional-theory (DFT) calculations of the electronic and optical properties are performed for these heterostructures. The results demonstrate that the photodetection response spectrum of the heterostructures is significantly broadened as the bandgap decreases from 2.17 to 0.40 eV for the $\mathrm{In}\mathrm{Se}$/${\mathrm{Cs}}_2{\mathrm{Sn}\mathrm{I}}_2{\mathrm{Cl}}_2$ heterostructure. Moreover, the electron effective mass, $m_e^{\ast }$, is reduced from 1.13 $m_0$ to 0.41 $m_0$ for the $\mathrm{In}\mathrm{Se}$/${\mathrm{Cs}}_2{\mathrm{Ge}\mathrm{I}}_2{\mathrm{Cl}}_2$ heterostructure. The significant reductions in both the band gap and effective mass are determined to be related to the type-II band alignment, which favors the carrier separation at the interface. The physical mechanisms related to the usage of this material in photodetectors are also discussed. The proposed III–VI semiconductor InSe and all-inorganic 2D RP perovskite ${\mathrm{Cs}}_{2}X{\mathrm{I}}_2{\mathrm{Cl}}_2$ (X = $\mathrm{Pb}$, $\mathrm{Sn}$, and $\mathrm{Ge}$) heterostructures provide challenges and opportunities for designing high-performance photodetectors.

中文翻译：

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基于InSe / Cs2XI2Cl2（X = Pb，Sn和Ge）异质结构的高性能光电探测器

近来，全无机二维（2D）Ruddlesden-Popper（RP）卤化物钙钛矿因其在环境空气中的出色稳定性而备受关注。但是，由于带隙宽和载流子迁移率低而产生的电子和光学性能阻碍了它们在光电探测器中的使用。为了克服这些限制，在这项工作中，应利用六方硒化铟（$在硒$）具有高电子迁移率，我们构建了原子薄的异质结构。对这些异质结构进行电子和光学性质的密度泛函理论（DFT）计算。结果表明，随着带隙从2.17 eV降低到0.40 eV，异质结构的光检测响应谱显着加宽。$在硒$/${\mathrm{Cs}}_2{锡\mathrm{一世}}_2{氯}_2$异质结构。此外，电子有效质量${米}_{Ë}^{\ast }$，从1.13减少 ${米}_0$ 至0.41 ${米}_0$ 为了 $在硒$/${\mathrm{Cs}}_2{\mathrm{通用电器}\mathrm{一世}}_2{氯}_2$异质结构。带隙和有效质量的显着降低被确定与II型带取向有关，这有利于界面处的载流子分离。还讨论了与在光电探测器中使用这种材料有关的物理机制。提议的III-VI半导体InSe和全无机2D RP钙钛矿${\mathrm{Cs}}_{2}X{\mathrm{一世}}_2{氯}_2$（X  = $\mathrm{铅含量}$， $锡$和 $\mathrm{通用电器}$）异质结构为设计高性能光电探测器带来了挑战和机遇。