Wang Ti, Jin Linrui, Hidalgo Juanita, Chu Weibin, Snaider Jordan M, Deng Shibin, Zhu Tong, Lai Barry, Prezhdo Oleg, Correa-Baena Juan-Pablo, Huang Libai
Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA.
School of Physics and Technology, Center for Nanoscience and Nanotechnology, and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072, China.
Sci Adv. 2020 Oct 23;6(43). doi: 10.1126/sciadv.abb1336. Print 2020 Oct.
Successful implementation of hot carrier solar cells requires preserving high carrier temperature as carriers migrate through the active layer. Here, we demonstrated that addition of alkali cations in hybrid organic-inorganic lead halide perovskites led to substantially elevated carrier temperature, reduced threshold for phonon bottleneck, and enhanced hot carrier transport. The synergetic effects from the Rb, Cs, and K cations result in ~900 K increase in the effective carrier temperature at a carrier density around 10 cm with an excitation 1.45 eV above the bandgap. In the doped thin films, the protected hot carriers migrate 100 s of nanometers longer than the undoped sample as imaged by ultrafast microscopy. We attributed these improvements to the relaxation of lattice strain and passivation of halide vacancies by alkali cations based on x-ray structural characterizations and first principles calculations.
热载流子太阳能电池的成功实施要求在载流子穿过有源层时保持较高的载流子温度。在此，我们证明在有机-无机杂化卤化铅钙钛矿中添加碱金属阳离子会导致载流子温度大幅升高、声子瓶颈阈值降低以及热载流子传输增强。铷、铯和钾阳离子的协同效应使得在载流子密度约为10/cm且激发能量比带隙高1.45 eV时，有效载流子温度升高约900 K。通过超快显微镜成像发现，在掺杂薄膜中，受保护的热载流子比未掺杂样品中的热载流子迁移距离长100纳米。基于X射线结构表征和第一性原理计算，我们将这些改进归因于碱金属阳离子对晶格应变的弛豫以及卤化物空位的钝化作用。
