双钙钛矿纳米材料的可控合成与光电特性研究

Perovskite solar cells (PSCs) have attracted tremendous attention in both academic and industrial community due to their high power conversion efficiencies (PCE) and low cost. PSCs usually employ the hybrid organic-inorganic metal halide perovskites (with ABX3 formulation) as light absorbing materials, such as the prototypic CH3NH3PbI3 (MAPbI3). However, PSCs face two main challenges toward its commercialization: the first one is the instability of perovskite materials; the second one is the toxicity of Pb2+. Thus, the development of lead-free perovskites without sacrificing device performance is attracting a lot of research interest. Double perovskite is considered to be a promising alternative light absorbing material due to its tunable bandgap, good ambient stability and environmentally friendly character. Herein we devote our efforts to the synthesis and optoelectronic properties of double perovskite nanomaterials. We will investigate the crystallization kinetics of double perovskite nanomaterials. Double perovskite nanocrystals will be prepared through solution-based method, and their quantum size effect and optoelectronic properties will be systematically studied. Furthermore, the potential application of these nanocrystals in optoelectronic devices will be demonstrated, such as solar cells.

钙钛矿太阳能电池由于其高光电转化效率和低成本的特点备受学术界和工业界的关注。该类型太阳能电池通常采用有机无机杂化钙钛矿材料作为光吸收层，典型的代表如CH3NH3PbI3（MAPbI3）。然而，钙钛矿太阳能电池目前面临两大挑战：一是其长期稳定性问题；二是铅的毒性问题。因此寻找能替代MAPbI3的钙钛矿材料显得尤为重要。双钙钛矿材料由于其光电性能优异、稳定性良好、环境友好等优点,被认为是潜在的能替代MAPbI3的材料。本项目以双钙钛矿纳米晶为切入点，探索该材料的合成及其光电性质。着重研究双钙钛矿纳米材料的结晶动力学问题，通过溶液相方法得到确定相态的双钙钛矿纳米材料，并研究其量子尺寸效应、光电特性，探讨其在太阳能电池等光电器件的应用前景。

寻找光电性能优异、环境友好的非铅钙钛矿材料具有重要意义。本研究首先对Cs2AgBiBr6纳米晶的合成进行了探索，成功制备出分散性较好的Cs2AgBiBr6纳米晶，并对其形貌、尺寸、相态、吸收光谱等做了基本表征。由于所制备的Cs2AgBiBr6纳米晶发光性能不佳，所以后期我们将研究体系聚焦于Cs4M2+M3+2X12(X=Cl, Br)层状双钙钛矿纳米晶和块体材料，成功合成得到Cs4CuSb2Cl12、Cs4MnBi2Cl12纳米晶，并对其基本光物理性质进行了研究。此外，本研究也探索了其他类钙钛矿金属卤化物的溶液法合成及其光电性质，例如Cs3Cu2Cl5体系，Cs5Cu3Cl6I2体系等。本研究对该类材料在辐射探测尤其是X射线探测与成像方面的应用做了初步研究。