Shil Sujit Kumer, Wang Fei, Egbo Kingsley O, Lai Zhengxun, Wang Ying, Wang Yunpeng, Zhao Dongxu, Tsang Sai-Wing, Ho Johnny C, Yu Kin Man
Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China.
Department of Physics, Khulna University of Engineering & Technology (KUET), Khulna 9203, Bangladesh.
ACS Appl Mater Interfaces. 2021 Aug 4;13(30):35930-35940. doi: 10.1021/acsami.1c07839. Epub 2021 Jul 21.
Lead-based halide perovskites (APbX, where A = organic or inorganic cation, X = Cl, Br, I) are suitable materials for many optoelectronic devices due to their many attractive properties. However, the concern of lead toxicity and the poor ambient and operational stability of the organic cation group greatly limit their practical utilization. Therefore, there has recently been great interest in lead-free, environment-friendly all-inorganic halide perovskites (IHPs). Sb and Sn are common species suggested to replace Pb for Pb-free IHPs. However, the large difference in the melting points of the precursor materials (e.g., CsBr and SbBr precursors for CsSbBr) makes the chemical vapor deposition (CVD) growth of high-quality Pb-free IHPs a very challenging task. In this work, we developed a two-step CVD method to overcome this challenge and successfully synthesized Pb-free CsSbBr perovskite microplates. CsSbBr microplates ∼25 μm in size with the exciton absorption peak at ∼2.8 eV and a band gap of ∼2.85 eV were obtained. The microplates have a smooth hexagonal morphology and show a large Stokes shift of ∼450 meV and exciton binding energy of ∼200 meV. To demonstrate the applications of these microplates in optoelectronics, simple photoconductive devices were fabricated. These photodetectors exhibit a current on/off ratio of 2.36 × 10, a responsivity of 36.9 mA/W, and a detectivity of 1.0 × 10 Jones with a fast response of rise and decay time of 61.5 and 24 ms, respectively, upon 450 nm photon irradiation. Finally, the CsSbBr microplates also show good stability in ambient air without encapsulation. These results demonstrate that the 2-step CVD process is an effective approach to synthesize high-quality all-inorganic lead-free CsSbBr perovskite microplates that have the potential for future high-performance optoelectronic device applications.
基于铅的卤化物钙钛矿（APbX，其中A =有机或无机阳离子，X = Cl、Br、I）因其诸多吸引人的特性而成为许多光电器件的合适材料。然而，铅毒性问题以及有机阳离子基团较差的环境稳定性和操作稳定性极大地限制了它们的实际应用。因此，近来人们对无铅、环境友好的全无机卤化物钙钛矿（IHPs）产生了浓厚兴趣。锑（Sb）和锡（Sn）是常用于替代无铅IHPs中铅的元素。然而，前驱体材料（例如用于CsSbBr的CsBr和SbBr前驱体）熔点的巨大差异使得高质量无铅IHPs的化学气相沉积（CVD）生长成为一项极具挑战性的任务。在这项工作中，我们开发了一种两步CVD方法来克服这一挑战，并成功合成了无铅CsSbBr钙钛矿微板。获得了尺寸约为25μm的CsSbBr微板，其激子吸收峰在约2.8eV处，带隙约为2.85eV。这些微板具有光滑的六边形形态，表现出约450meV的大斯托克斯位移和约200meV的激子结合能。为了展示这些微板在光电子学中的应用，制作了简单的光电导器件。在450nm光子照射下，这些光电探测器的电流开/关比为2.36×10，响应度为36.9mA/W，探测率为1.0×10琼斯，上升和衰减时间的快速响应分别为61.5和24ms。最后，CsSbBr微板在未封装的环境空气中也表现出良好的稳定性。这些结果表明，两步CVD工艺是合成高质量全无机无铅CsSbBr钙钛矿微板的有效方法，这些微板具有未来高性能光电器件应用的潜力。
