无机半导体/无铅钙钛矿双异质结型绿光LED的制备及其发光机制研究

Due to the high color rendering index and luminescence efficiency, white light-emitting diodes (LED) combined by red, green, blue multi-chips have been regarded as the trends of solid-state lighting. However, the development of more efficient green LEDs is one of the challenges. Recently, organic-inorganic hybrid perovskite has become the hottest research topic in the new photovoltaic device due to their perfect light absorption and charge transfer optoelectronic properties. In addition, previous works have shown these perovskites possess special photoluminescent properties, making them potential candidates for light-emitting devices with high efficiency. In this project, the perovskite green LEDs with double heterojunction structure will be fabricated using wide-bandgap lead-free perovskite CH3NH3SnX3 (X is Br or Cl) as the emitting layer, and inorganic semiconductors as carrier injection layer. Furthermore, influence of interface on the electroluminescence of perovskite LEDs will be systemically studied by optimizing the growth parameters and device process. Finally, the energy band model of heterojunction will be constructed for illuminating the mechanism of the carrier transport, recombination characteristics and luminescence properties of perovskite LEDs. The results found in this research will provide theoretical basis and technical support for preparing of green LEDs based on lead-free perovskite with low-cost and high brightness.

利用红、绿、蓝多芯片LED合成白光可获得较高的显色指数和发光效率，被认为是固体照明技术的未来发展方向。然而，绿光LED的效率问题仍是阻碍其发展和应用的瓶颈。近年来，有机-无机杂化钙钛矿材料因其优良的光学吸收和电荷传导特性而成为新型光伏器件领域的研究热点。此外，该材料还表现出特殊的发光特性，被认为是实现高效发光器件的理想半导体材料。本项目拟采用宽带隙的无铅钙钛矿材料CH3NH3SnX3（X为Br或Cl）作为发光层，并选用无机半导体材料作为载流子注入层，研制具有双异质结结构的钙钛矿型绿光LED；通过优化材料生长参数及器件制备工艺，系统地研究材料界面对钙钛矿LED发光性能的影响；最后，建立合理的异质结能带模型，阐释无机半导体/无铅钙钛矿双异质结型绿光LED载流子输运、复合及发光的微观物理机制。本项目将为研制低成本、高亮度的钙钛矿型绿光LED提供理论依据和技术支持。

由于具有特殊的光电性能，钙钛矿材料在太阳能电池、发光二极管、激光器和光电探测器领域得到了广泛的关注。本项目中，我们利用脉冲激光沉积技术制备了全无机钙钛矿薄膜材料，并研究了材料的形貌结构及其光电性能。利用制备的钙钛矿薄膜材料，设计并制备了不同结构的钙钛矿异质结光电器件，如光电探测器及发光二极管，并初步研究了器件的光电性能。其中CsPbBr3/n-Si异质结探测器在绿光波段表现出较高的探测率；n-ZnO/i-CsPbBr3/p-GaN异质结发光二极管在正向电压下表现出430nm附近的紫光发射，而在反向电压下实现了500nm-700nm区间的黄绿光发射。此外，一些用来制备钙钛矿异质结的无机半导体材料如CuI，SnO2等也在本项目中做了研究。本项目实验结果将为利用PLD制备钙钛矿光电器件提供理论基础和技术支持。