Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes
Two-Step Crystallization for Low-Oxidation Tin-Based Perovskite Light-Emitting Diodes
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DOI：
10.1021/acsami.1c22130
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发表时间：
2022-01-25
影响因子：
9.5
通讯作者：
Kido, Junji
中科院分区：
文献类型：
--
作者：
Cheng, Yu-Hong;Moriyama, Reine;Kido, Junji
金属卤化物钙钛矿材料因其优异的光电和半导体性能而受到广泛关注。然而，存在与主要用于这些钙钛矿中的铅金属的毒性相关的环境问题。PEA（2）SnI（4）钙钛矿由于其纯红色发射而成为无铅钙钛矿的潜在候选者。然而，不期望的Sn 4+氧化导致PEA（2）SnI（4）钙钛矿的劣化。我们证明了PEA（2）SnI（4）通过（i）再沉淀和（ii）重结晶过程的两步结晶。使用该方法制备的膜由于其均匀发射而表现出窄发射，半峰全宽为30.0至26.1 nm。此外，两步结晶的PEA（2）SnI（4）膜的Sn 4+含量比对照膜低5倍。扩散有序光谱分析表明，两步前体具有较小的流体动力学半径的晶种，这增强了旋涂过程中的结晶。所得的两步结晶PEA（2）SnI（4）基发光二极管（LED）表现出0.4%的最大外量子效率（EQE），平均为0.2%，这是对照器件的两倍。这种两步法可以推广到合成其他无铅材料。
Metal halide perovskites attract significant attention because of their excellent optoelectronic and semiconducting properties. However, there are environmental concerns related to the toxicity of the lead metal that is mainly used in these perovskites. PEA(2)SnI(4) perovskite is a potential candidate for lead-free perovskites because of its pure red emission. Although, undesired Sn4+ oxidation results in the deterioration of PEA(2)SnI(4) perovskite. We demonstrate the two-step crystallization of PEA(2)SnI(4) through the (i) reprecipitation and (ii) recrystallization processes. A film prepared using this method exhibits narrowed emission, with a full width at half-maximum from 30.0 to 26.1 nm, because of its homogeneous emission. Moreover, the Sn4+ content of two-stepcrystallized PEA(2)SnI(4) films is five times lower than that of a control film. Diffusion-ordered spectroscopy analysis indicates that the two-step precursor exhibits a smaller hydrodynamic radius crystal seed, which enhances crystallization during spin coating. The resulting two-step crystallized PEA(2)SnI(4)-based light-emitting diode (LED) exhibits a maximum external quantum efficiency (EQE) of 0.4% with an average of 0.2%, which is two times greater than that of the control device. This two-step approach may be generalized to synthesize other lead-free materials.