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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Two Regimes of Carrier Diffusion in Vapor-Deposited Lead-Halide Perovskites
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Two Regimes of Carrier Diffusion in Vapor-Deposited Lead-Halide Perovskites

机译：气相沉积的卤化卤酸钙锌矿中的两个载流子扩散制度

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Metal halide perovskites are attractive materials for the realization of cheap and effective solar cells, thin film transistors, and light emitters. Carrier diffusion at high excitations, however, is poorly addressed in perovskites, even though it governs the diffusion length and determines the efficiency of photonic devices. To fully understand the dependence of diffusion length on carrier density, we performed direct and independent measurements of the carrier diffusion coefficient and recombination rate in several methylammonium lead halide perovskite layers by applying the light-induced transient grating technique. We demonstrate the existence of two distinct carrier diffusion regimes within the density range of 10(18)-10(20) cm(-3). In the perovskite films of high compositional quality, diffusion is governed by a bandlike transport of free carriers. The diffusivity is high (0.28-0.7 cm(2)/s) in these samples, even at low carrier density, and further increases with excitation due to carrier degeneracy. The opposite scenario was observed in disordered perovskite layers, where diffusion is governed by hopping-like transport of localized carriers. The diffusion coefficient in latter layers is small (0.01-0.04 cm(2)/s at low densities) and increases with excitation due to local state filling and carrier delocalization. We show that carrier recombination can be well-described using the nonlinear radiative and nonradiative recombination coefficients that saturate with excitation due to phase space filling at high carrier densities. On the basis of these findings, we provide recommendations for the maximization of carrier diffusion length in different perovskites.
机译：金属卤化物佩罗夫斯基斯是实现便宜且有效的太阳能电池，薄膜晶体管和光发射器的吸引力。然而，在高激发下的载流子扩散在Perovskites中似乎很差，即使它控制扩散长度并确定光子器件的效率。为了充分了解扩散长度对载体密度的依赖性，通过施加光引起的瞬态光栅技术，我们在几种甲基丙酰卤化卤化卤化物层中进行直接和独立的测量。我们证明了在10（18）-10（20）厘米（-3）的密度范围内的两个不同载流子扩散制度的存在。在高成分质量的Perovskite薄膜中，扩散受到游离载体的带状运输的管辖。即使在低载体密度下，这些样品中的扩散率高（在这些样品中为0.28-0.7cm（2）/ s），并且由于载体退化而进一步随着激发而增加。在无序的钙钛矿层中观察到相反的情况，其中扩散通过局部载体的跳跃式运输来治理。后一层的扩散系数小（低密度为0.01-0.04cm（2）/ s），并且由于局部填充和载体临床化，随着激励而增加。我们表明，可以使用由于在高载体密度下填充的相空间而饱和的非线性辐射和非相互作用重组系数来稳定地描述载体重组。在这些调查结果的基础上，我们提供了建议在不同钙钛矿中最大化载波扩散长度的建议。

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