基于微波介电法的光生载流子复合动力学诊断

发布时间：2018-01-27 11:43

本文关键词： 微波介电谱载流子钙钛矿薄膜　出处：《河北大学》2017年硕士论文　论文类型：学位论文

【摘要】：微波介电谱测量技术是一种基于微波与物质材料相互作用的测量技术。该测量技术具有非接触测量,信号采集速度快和测量时间分辨高等优点。因此,微波介电谱测量技术在光电功能材料载流子复合动力学诊断领域具有良好的应用前景。本文首先根据半导体光生载流子复合动力学的微波介电谱测量原理,搭建了微波介电谱测量系统,其中包括相关微波器件的选择和微波介电谱测量系统的测试两部分。在微波器件选择方面,微波谐振腔是微波介电谱测量系统中的核心部件。本文使用High Frequency Structure Simulator(HFSS)软件对微波谐振腔中的电磁场分布进行了模拟仿真。仿真结果显示,仿真优化结果与理论计算值一致;在TE103谐振模式下,谐振腔内电磁场分布的仿真结果显示,电场强度最强的位置位于谐振腔的中央位置,并以此作为谐振腔侧壁开缝的依据。在纳秒脉冲(脉冲宽度5-7 ns)激发条件下,微波介电谱测量系统的时间分辨率可以到达15 ns(高斯型仪器响应函数,半高全宽),在飞秒脉冲(脉冲宽度小于100 fs)激发条件下,系统测量时间分辨率可以达到1-2 ns。有机金属卤化物钙钛矿(CH_3NH_3PbX_3,X-Cl、Br、I)作为一种新兴的光伏材料,是目前太阳能电池领域研究的重点。对钙钛矿薄膜光生载流子复合动力学的研究可以为钙钛矿太阳能电池的设计与生产提供有力的科学依据。本文利用搭建的微波介电谱测量系统,对有机金属卤化物钙钛矿薄膜材料的载流子复合动力学进行了研究,工作主要分为三个部分:(1)本文利用微波介电谱测量技术,从光生载流子复合动力学的角度说明了Cl元素的掺入对钙钛矿薄膜光物理特性的影响。实验结果显示,相比CH_3NH_3PbI_3钙钛矿薄膜,CH_3NH_3PbI_(3-x)Cl_x钙钛矿薄膜的自由载流子复合寿命从67 ns增加到157 ns,浅束缚能级(束缚能级深度5-30 meV)载流子复合寿命从290 ns增加到492 ns。此外,通过对比CH_3NH_3PbI_3和CH_3NH_3PbI_(3-x)Cl)x钙钛矿薄膜的光生载流子复合动力学还发现,后者浅束缚能级载流子的热活化过程对载流子复合动力学影响更为显著。因此可以推断,Cl元素的掺杂在薄膜中引入了更多的浅束缚态,同时减少了深束缚态密度。(2)本文在共振激发模式下和非共振激发模式下对CH_3NH_3PbBr_3钙钛矿薄膜的光生载流子复合动力学进行了测量。实验结果表明,光生载流子复合过程分为一个快速衰减阶段和一个缓慢衰减阶段。当自由载流子浓度减少到一定程度后,自由载流子与浅束缚能级(束缚能级深度5-30 meV)载流子达到热平衡。具体而言,在共振激发模式下(558 nm),自由载流子和浅束缚能级载流子达到热平衡所需要的时间大约是56 ns;而在非共振激发下(355 nm),自由载流子和浅束缚能级载流子达到热平衡所需要的时间更长,大约是848 ns。(3)本文还研究了CH_3NH_3PbI_3钙钛矿薄膜经过光浴-暗置处理后薄膜的光生载流子复合动力学变化。实验结果显示,光浴-暗置后钙钛矿薄膜的光生载流子产率有了明显的增加,但随着再次光浴处理光生载流子产率快速降低。
[Abstract]:Microwave dielectric spectrum measurement technique is a measurement of microwave interaction with materials. Based on the measurement technology with non contact measurement, signal acquisition speed and the measurement of time resolved advantages. Therefore, microwave dielectric spectrum measurement technology in photoelectric functional material carrier composite dynamic diagnosis field has a good application prospect in this paper. According to the semiconductor minority carrier recombination kinetics of microwave dielectric spectrum measurement principle, build a microwave dielectric spectrum measurement system, including two parts related to microwave devices and microwave dielectric spectrum measurement system. In the aspect of the selection of microwave devices, microwave resonant cavity microwave dielectric spectrum measurement is the core component in the system this paper uses the High Frequency Structure. Simulator (HFSS) software of electromagnetic field distribution in the microwave cavity is simulated. The simulation results show that the imitation So the optimization results are consistent with theoretical values; in TE103 resonant mode, the resonant cavity of the electromagnetic field simulation results show that the electric field intensity of the strongest position is located in the cavity of the central position, and as the cavity side wall slot basis. In nanosecond pulse (pulse width of 5-7 NS) under the excitation of dielectric, time resolution the microwave spectrum measurement system can reach 15 ns (Gauss type instrument response function, full width at half maximum), in the femtosecond pulse (pulse width less than 100 fs) under the excitation system, the measuring time resolution can reach 1-2 ns. organic metal halide perovskite (CH_3NH_3PbX_3, X-Cl, Br, I) is a kind of new photovoltaic materials. Is the focus of current research in the field of solar cells. Provide scientific basis for the design and production of Perovskite Thin Films of photogenerated carrier recombination dynamics for perovskite solar cells. In this paper, using microwave dielectric structures of the spectrum measurement system, carrier recombination kinetics of organic metal halide perovskite thin films were studied. The main work is divided into three parts: (1) using microwave dielectric spectrum measurement technology, from the minority carrier recombination dynamics point of view that the incorporation of Cl effect on the photophysical properties of Perovskite Thin Films. The experimental results show that compared with CH_3NH_3PbI_3 Perovskite Thin Films, CH_3NH_3PbI_ (3-x) Cl_x free carrier recombination lifetime of Perovskite Thin films increased from 67 ns to 157 ns, shallow levels (levels of depth 5-30 meV) the carrier lifetime increased from 290 ns to 492 ns. in addition, through the comparison of CH_3NH_3PbI_3 and CH_3NH_3PbI_ (3-x) Cl) x perovskite films photogenerated carrier recombination dynamics also found that the shallow levels of the carrier thermal activation process of the carrier recombination dynamics. Sound is more significant. So it can be inferred that Cl doping introduced shallow bound more in the film, while reducing the depth bound density. (2) the light of CH_3NH_3PbBr_3 Perovskite Thin Films in the resonant excitation mode and excitation mode of non resonance carrier recombination dynamics were measured. The experimental results show that that the minority carrier recombination process into a rapid decay phase and a slow decay stage. When reducing the free carrier concentration to a certain extent, free carrier and shallow levels (levels of depth 5-30 meV) carrier to reach thermal equilibrium. Specifically, the resonance excitation mode (558 nm), free the carrier and shallow levels of carriers to reach the thermal equilibrium time required is about 56 ns; and in the non resonant excitation (355 nm), the free carrier and shallow levels of carrier to reach thermal balance A longer period of time, is about 848 ns. (3) this paper also studied the CH_3NH_3PbI_3 Perovskite Thin Films after dark the light bath after treatment thin film composite carrier dynamics. The experimental results show that the light - Dark bath after the Perovskite Thin Films of photoexcited carriers yield has increased significantly, but again with light light bath treatment carrier yield decreased rapidly.

【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.2;O649.5

【参考文献】