全无机钙钛矿纳米晶材料中非平衡态载流子的超快光电动力学研究

Due to their outstanding opto-electronic properties and potential applications in photoelectric devices, all inorganic perovskite nanomaterials have attracted much attention. In this project, we choose the all inorganic perovskite nanocrystals, thin films, and the corresponding opto-electronic devices as object and employ the single photon counting time resolution technique, femtosecond pump detection technology, and ultrafast transient photocurrent detection technology based on high frequency sampling oscilloscope to investigate the ultrafast photoelectrical dynamics properties of non-equilibrium carriers in the materials of all inorganic perovskite nanocrystals. The specific research includes:.(1) Preparation and characterization of perovskite nanocrystals, films and the corresponding photoconductive devices;.(2) Study on the ultrafast relaxation characteristics of perovskite nanocrystals in solution and film form;.(3) Study on the ultrafast photoelectrical dynamics properties of carriers in photoconductive devices based on perovskite nanocrystal films;.We use multi-manners to test the transient opto-electronic dynamics in the novel opto-electronic materials and further clarify the adjusting effect and mechanism of the nanocrystal component, shape on its optoelectronic property. The aim of our project is to study the physical mechanism behind the experimental phenomenon. The final results would offer the theoretical and experimental evidence for these materials in the lighting, display and other optoelectronic fields.

由于全无机钙钛矿纳米晶作为新型的半导体材料在光电器件领域中具有潜在的应用前景而引起人们的广泛关注。本项目以全无机钙钛矿纳米晶、纳米晶薄膜、纳米晶薄膜光电器件为研究对象，利用单光子计数时间分辨、飞秒泵浦探测、超快瞬态光电流探测等多种技术手段，研究全无机钙钛矿纳米晶材料及器件中非平衡态载流子的超快光电动力学规律。具体研究内容包括：.（1）钙钛矿纳米晶、纳米晶薄膜材料、纳米晶薄膜光电导器件的制备.（2）钙钛矿纳米晶分别在溶液和薄膜状态下的载流子超快动力学研究.（3）钙钛矿纳米晶薄膜光电导器件中的载流子超快光电动力学研究.通过以多种联合技术手段对新型钙钛矿纳米晶光电导材料的超快动力学的实验检测和规律的总结，解析纳米晶材料的组份、尺寸、形貌对器件光电特性调节作用的物理机理是本项目的研究特色。研究成果为此类材料在照明、显示和其他光电子领域的应用提供实验依据和理论指导。

钙钛矿材料近期在半导体光电子领域凸显了越来越出色的性能，其太阳电池和LED器件的性能不断攀升，其性能逐年增强的核心在于其卓越的载流子特性，为此开展钙钛矿纳米晶载流子特性的研究十分必要。本项目针对钙钛矿纳米晶的载流子动力学特性开展了丰富的研究工作。具体研究总结如下：（1）合成了一系列全无机钙钛矿纳米晶、Cs2AgBiBr6 双钙钛矿纳米晶、Cs4CuxAg2–2xSb2Cl12 双钙钛矿纳米晶、MAPbX3钙钛矿纳米晶、FAPbX3钙钛矿纳米晶、CsPbBr3六方纳米晶、CsPbBr3立方纳米晶、PBA2(MAPbBr3)n-1PbBr4钙钛矿薄膜等不同形貌和不同成份的纳米尺度的钙钛矿材料；并利用稳态吸收和稳态发射等多种测量手段研究了这些半导体纳米晶的形貌、尺寸和化学成分与其能态的内在联系。基于飞秒泵浦-探测技术和皮秒时间分辨荧光技术研究了化学组份、晶体形貌、粒径尺寸等因素的调控下，钙钛矿纳米晶在溶液中的超快激子弛豫特性，同时分析了高能和低能激子的弛豫特性、多激子下的碰撞和弛豫机制。（2）此外我们还制备了相应的纳米晶薄膜，并利用常温和变温的瞬态吸收光谱研究技术研究了钛矿纳纳米晶薄膜中的单分子、双分子和俄歇复合等载流子复合动力学过程，还有热载流子弛豫过程等载流子动力学过程，解析比较不同形貌、尺寸及化学成分的钙钛矿纳米晶薄膜中的超快载流子动力学特性，在薄膜中不同载流子浓度下，研究载流子的动力学机制尤其是载流子复合机制以及热载流子弛豫机制与材料形貌、尺寸及化学成份之间的内在联系，分析和确定观察到的光谱现象的内在物理本质。（3）制备基于钙钛矿纳米晶的光电探测器，开展了温度依赖、光强依赖、电压依赖的光电特性研究，探讨了温度诱导的相变对钙钛矿纳米晶薄膜光电特性的调控机制。