2D perovskites recently receive significant research attention due to their unique semiconducting properties and superior stability than 3D counterparts (ABX₃). In this study, a rare 2D Cs₂Pb(SCN)₂Br₂ is prepared by partially substituting X-site halide anion with an asymmetric pseudo-halide anion, SCN^-. Such 2D Cs₂Pb(SCN)₂X₂ possess not only an all-inorganic structure but also a much smaller spacing between perovskite sheets among the reported 2D perovskites comprising large A-site organic cations. This stable 2D Cs₂Pb(SCN)₂Br₂ is integrated with MoS₂ to constitute an all-inorganic 2D heterojunction, and this all-inorganic 2D heterojunction is shown to greatly improve the performance of MoS₂-based photodetector, wherein 2D Cs₂Pb(SCN)₂Br₂ serves as light absorbing layer with regard to its intense light-harvesting property and MoS₂ functions as the transport layer with regard to its remarkable electrical properties. That is, Cs₂Pb(SCN)₂Br₂ serves as a photo-gating layer to modulate the conductive behavior of MoS₂. It reveals a type-II energy band alignment formed between Cs₂Pb(SCN)₂Br₂ and MoS₂ enables efficient charge transfer from Cs₂Pb(SCN)₂Br₂ to MoS₂. Besides, Cs₂Pb(SCN)₂Br₂ seems to passivate the surface defects on MoS₂ to facilitate interfacial charge transfer. As a result, the hybrid photodetector exhibits an impressively high responsivity of 1.22 × 10⁵ A W^-1 with response time shortened to ms, among the best values reported for perovskite/MoS₂ hybrid photodetectors. This encouraging result paves a new avenue for all-inorganic 2D perovskite-based optoelectronic devices.

2D钙钛矿由于其独特的半导体特性和比3D钙钛矿（ABX ₃）优越的稳定性，最近受到了广泛的研究关注。在这项研究中，罕见2D铯₂的Pb（SCN）₂溴₂是通过用非对称伪卤化物阴离子，SCN部分取代X现场卤化物阴离子制备^- 。这样的2D Cs ₂ Pb（SCN）₂ X ₂不仅具有全无机结构，而且在所报告的包含大的A位有机阳离子的2D钙钛矿中，钙钛矿片之间的间距小得多。此稳定的2D Cs ₂ Pb（SCN）₂ Br ₂与MoS集成在一起_图2所示的结构构成全无机2D异质结，并且该全无机2D异质结显示出极大地提高了基于MoS ₂的光电探测器的性能，其中2D Cs ₂ Pb（SCN）₂ Br ₂用作吸光层。凭借其出色的电学性能，其强大的集光性能和MoS ₂充当了传输层。即，Cs ₂ Pb（SCN）₂ Br ₂用作光门控层以调节MoS ₂的导电行为。它揭示了Cs ₂ Pb（SCN）₂ Br之间形成的II型能带排列借助图₂和MoS _2，可以有效地将电荷从Cs ₂ Pb（SCN）₂ Br ₂转移到MoS ₂。此外，Cs ₂ Pb（SCN）₂ Br ₂似乎可以钝化MoS ₂上的表面缺陷，从而促进界面电荷转移。结果，在报道的钙钛矿/ MoS ₂混合光电探测器的最佳值中，混合光电探测器表现出令人印象深刻的高响应度，为1.22×10 ⁵ AW ^-1，响应时间缩短至ms 。这一令人鼓舞的结果为基于全无机2D钙钛矿的光电器件开辟了一条新途径。