Department of Physics, National University of Singapore, Singapore, 117551, Singapore.
Department of Chemistry, National University of Singapore, Singapore, 117546, Singapore.
Adv Mater. 2019 Nov;31(48):e1904155. doi: 10.1002/adma.201904155. Epub 2019 Oct 8.
Two-dimensional (2D) perovskites have proved to be promising semiconductors for photovoltaics, photonics, and optoelectronics. Here, a strategy is presented toward the realization of highly efficient, sub-bandgap photodetection by employing excitonic effects in 2D Ruddlesden-Popper-type halide perovskites (RPPs). On near resonance with 2D excitons, layered RPPs exhibit degenerate two-photon absorption (D-2PA) coefficients as giant as 0.2-0.64 cm MW . 2D RPP-based sub-bandgap photodetectors show excellent detection performance in the near-infrared (NIR): a two-photon-generated current responsivity up to 1.2 × 10 cm W s , two orders of magnitude greater than InAsSbP-pin photodiodes; and a dark current as low as 2 pA at room temperature. More intriguingly, layered-RPP detectors are highly sensitive to the light polarization of incoming photons, showing a considerable anisotropy in their D-2PA coefficients (β /β = 2.4, 70% larger than the ratios reported for zinc-blende semiconductors). By controlling the thickness of the inorganic quantum well, it is found that layered RPPs of (C H NH ) (CH NH )Pb I can be utilized for three-photon photodetection in the NIR region.
二维（2D）钙钛矿已被证明是用于光伏、光子学和光电的有前途的半导体。在这里，提出了一种策略，通过在二维类钙钛矿卤化物钙钛矿（RPP）中利用激子效应来实现高效的亚带隙光电探测。在与二维激子近共振时，层状 RPP 表现出高达 0.2-0.64 cmMW 的简并双光子吸收（D-2PA）系数。基于 2D RPP 的亚带隙光电探测器在近红外（NIR）区域表现出优异的检测性能：双光子产生的电流响应率高达 1.2×10cmWs，比 InAsSbP 光电二极管高两个数量级；在室温下暗电流低至 2pA。更有趣的是，层状-RPP 探测器对入射光子的光偏振高度敏感，其 D-2PA 系数表现出相当大的各向异性（β/β=2.4，比报道的闪锌矿半导体的比值大 70%）。通过控制无机量子阱的厚度，发现（CHNH）（CHNH）PbI 的层状 RPP 可用于近红外区域的三光子光电探测。
