Photodoping through local charge carrier accumulation in alloyed hybrid perovskites for highly efficient luminescence
Photodoping through local charge carrier accumulation in alloyed hybrid perovskites for highly efficient luminescence
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DOI：
10.1038/s41566-019-0546-8
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发表时间：
2020-02-01
期刊：
影响因子：
35
通讯作者：
Deschler, Felix
中科院分区：
文献类型：
--
作者：
Feldmann, Sascha;Macpherson, Stuart;Deschler, Felix
混合阳离子钙钛矿中的局域光掺杂改变了电荷-载流子复合，从而为更有效的发光提供了一条途径。金属卤化物钙钛矿已经成为一种特殊的半导体材料，在光电子学中的应用。取代单价阳离子具有更高的发光产率和器件效率。在这里，我们通过改变混合卤化物钙钛矿中的电荷载流子动力学来控制阳离子合金化来提高光电性能。与单一卤化物钙钛矿相比，我们发现，在远低于太阳光照条件下，光激发载流子密度具有高的发光产额。利用时间分辨光谱分析表明，在激发后的前几十纳秒内，载流子复合区域从二阶变为一阶。在光学带隙的微观标绘、电学门控输运测量和第一性原理计算的支持下，我们证明了电子态中空间变化的能量无序导致局部电荷积累，产生了p型和n型光掺杂区域，从而揭示了在太阳能电池和发光二极管中低电荷注入时高效发光的策略。
Localized photodoping in mixed-cation perovskites is shown to modify charge-carrier recombination and thus offer a route for more efficient light emission.Metal halide perovskites have emerged as exceptional semiconductors for optoelectronic applications. Substitution of the monovalent cations has advanced luminescence yields and device efficiencies. Here, we control the cation alloying to enhance optoelectronic performance through alteration of the charge carrier dynamics in mixed-halide perovskites. In contrast to single-halide perovskites, we find high luminescence yields for photoexcited carrier densities far below solar illumination conditions. Using time-resolved spectroscopy we show that the charge carrier recombination regime changes from second to first order within the first tens of nanoseconds after excitation. Supported by microscale mapping of the optical bandgap, electrically gated transport measurements and first-principles calculations, we demonstrate that spatially varying energetic disorder in the electronic states causes local charge accumulation, creating p- and n-type photodoped regions, which unearths a strategy for efficient light emission at low charge-injection in solar cells and light-emitting diodes.