Bi Yu, Hutter Eline M, Fang Yanjun, Dong Qingfeng, Huang Jinsong, Savenije Tom J
Optoelectronic Materials Section, Department of Chemical Engineering, Delft University of Technology , 2628 BL Delft, The Netherlands.
Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln , Nebraska 68588-0656, United States.
J Phys Chem Lett. 2016 Mar 3;7(5):923-8. doi: 10.1021/acs.jpclett.6b00269. Epub 2016 Feb 24.
The charge carrier lifetime in organic-inorganic perovskites is one of the most important parameters for modeling and design of solar cells and other types of devices. In this work, we use CH3NH3PbI3 single crystal as a model system to study optical absorption, charge carrier generation, and recombination lifetimes. We show that commonly applied photoluminescence lifetime measurements may dramatically underestimate the intrinsic carrier lifetime in CH3NH3PbI3, which could be due to severe charge recombination at the crystal surface and/or fast electron-hole recombination close to the surface. By using the time-resolved microwave conductivity technique, we investigated the lifetime of free mobile charges inside the crystals. Most importantly, we find that for homogeneous excitation throughout the crystal, the charge carrier lifetime exceeds 15 μs. This means that the diffusion length in CH3NH3PbI3 can be as large as 50 μm if it is no longer limited by the dimensions of the crystallites.
有机-无机钙钛矿中的电荷载流子寿命是用于太阳能电池及其他类型器件建模与设计的最重要参数之一。在本工作中，我们使用CH3NH3PbI3单晶作为模型体系来研究光吸收、电荷载流子产生及复合寿命。我们表明，常用的光致发光寿命测量可能会显著低估CH3NH3PbI3中的本征载流子寿命，这可能是由于晶体表面的严重电荷复合和/或靠近表面的快速电子-空穴复合所致。通过使用时间分辨微波电导率技术，我们研究了晶体内部自由移动电荷的寿命。最重要的是，我们发现对于整个晶体的均匀激发，电荷载流子寿命超过15 μs。这意味着如果不再受微晶尺寸限制，CH3NH3PbI3中的扩散长度可高达50 μm。
