MA_(0.6)Cs_(0.4)PbBr_3钙钛矿发光二极管瞬态电致发光研究

Investigation on Transient Electroluminescence from Perovskite Light Emitting Diode Based on MA_(0.6)Cs_(0.4)PbBr_3

为研究钙钛矿材料的发光特性和机理,制备了稳定的MA_(0.6)Cs_(0.4)Pb Br_3钙钛矿发光二极管,通过瞬态电致发光测试,分析了器件在脉冲电压下的电流和发光曲线。MA_(0.6)Cs_(0.4)Pb Br_3发光二极管在恒定的电流密度10 m A·cm^(-2)下,亮度从最大值衰减至一半持续时间超过30 min,保证了瞬态测试的准确性。在0.1～20 ms脉宽测试中,器件发光效率随时间增加,断电后有反向电流;在5.5～8.0 V的脉冲幅值测试中,低电压的亮度最先达到饱和;在0～2.0 V基准电压测试中,高基准电压时亮度值更低。分析瞬态测试结果,发现离子迁移(MA^+,Br^-)导致钙钛矿层的界面附近发生能带弯曲,使得载流子注入减弱,同时抑制了激子的离化,提高了激子复合几率。

In order to analyze the luminescent characteristics and mechanism of perovskite materials,a stable perovskite light emitting diode was prepared.The transient current and transient electroluminescence of the device driven by electric pulsed are investigated.At a constant current density of 10 m A·cm-2,the luminance attenuated from the maximum to half in a duration of more than 30 min,which ensure the accuracy of the transient test.In the 0.1~20 ms pulse width,the luminous efficiency of the device increases with time,and there is a reverse current after power turnoff.In the pulse amplitude test,the brightness of low voltage easily reaches its saturation.In the offset voltage test,the intensity of electroluminescence at high offset voltage is lower than that at low offset voltage.Analyzing the transient test results,we can conclude that ion migration(MA+,Br-)leads to the bending of energy band in the interface of the perovskite layer,which weakens the carrier injection.Meanwhile,the exciton dissociation is suppressed,leading an increase in the electroluminescence efficiency.