Liao Chwen-Haw, Chen Chiung-Han, Bing Jueming, Bailey Christopher, Lin Yi-Ting, Pandit Twishi Mukul, Granados Laura, Zheng Jianghui, Tang Shi, Lin Bi-Hsuan, Yen Hung-Wei, McCamey Dane R, Kennedy Brendan J, Chueh Chu-Chen, Ho-Baillie Anita W Y
School of Physics University of Sydney Nano Institute, The University of Sydney, Sydney, NSW, 2006, Australia.
Department of Chemical Engineering, National Taiwan University, Taipei, 106, Taiwan.
Adv Mater. 2022 Feb;34(7):e2104782. doi: 10.1002/adma.202104782. Epub 2021 Dec 21.
Most of the reported 2D Ruddlesden-Popper (RP) lead halide perovskites with the general formula of A B X (n = 1, 2, …) comprise layered perovskites separated by A-site-substituted organic spacers. To date, only a small number of X-site-substituted RP perovskites have been reported. Herein, the first inorganic-cation pseudohalide 2D phase perovskite single crystal, Cs Pb(SCN) Br , is reported. It is synthesized by the antisolvent vapor-assisted crystallization (AVC) method at room temperature. It exhibits a standard single-layer (n = 1) Ruddlesden-Popper structure described in space group of Pmmn (#59) and has a small separation (d = 1.69 Å) between the perovskite layers. The SCN anions are found to bend the 2D Pb(SCN) Br framework slightly into a kite-shaped octahedron, limiting the formation of a quasi-2D perovskite structure (n > 1). This 2D single crystal exhibits a reversible first-order phase transformation to 3D CsPbBr (Pm3m #221) at 450 K. It has a low exciton binding energy of 160 meV-one of the lowest for 2D perovskites (n = 1). A Cs Pb(SCN) Br -single-crystal photodetector is demonstrated with respectable responsivity of 8.46 mA W and detectivity of ≈1.2 × 10 Jones at a low bias voltage of 0.5 V.
大多数报道的通式为AₙBₙ₊₁X₃ₙ₊₁（n = 1, 2, …）的二维Ruddlesden-Popper（RP）铅卤化物钙钛矿由A位取代的有机间隔层分隔的层状钙钛矿组成。迄今为止，仅报道了少量X位取代的RP钙钛矿。在此，报道了首例无机阳离子拟卤化物二维相钙钛矿单晶CsPb(SCN)₂Br₂。它是通过反溶剂气相辅助结晶（AVC）法在室温下合成的。它呈现出空间群为Pmmn（#59）所描述的标准单层（n = 1）Ruddlesden-Popper结构，且钙钛矿层之间的间距较小（d = 1.69 Å）。发现SCN阴离子将二维Pb(SCN)₂Br₂骨架轻微弯曲成风筝形八面体，限制了准二维钙钛矿结构（n > 1）的形成。这种二维单晶在450 K时表现出向三维CsPbBr₃（Pm3m #221）的可逆一级相变。它具有160 meV的低激子结合能——是二维钙钛矿（n = 1）中最低的之一。展示了一种CsPb(SCN)₂Br₂单晶光电探测器，在0.5 V的低偏置电压下具有8.46 mA W的可观响应度和约1.2×10¹² Jones的探测率。
