Light-Bias-Dependent External Quantum Efficiency of Kesterite Cu2ZnSnS4 Solar Cells
Light-Bias-Dependent External Quantum Efficiency of Kesterite Cu2ZnSnS4 Solar Cells
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DOI：
10.1021/acsphotonics.7b00151
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发表时间：
2017-07-01
期刊：
影响因子：
7
通讯作者：
Green, Martin A.
中科院分区：
文献类型：
--
作者：
Liu, Fangyang;Yan, Chang;Green, Martin A.
报道了采用不同缓冲层的锌黄锡矿Cu_2ZnSnS_4太阳电池的外量子效率随光偏压的变化。在红光偏置下，由于缓冲层的光电导性增加耗尽区宽度并由此增加收集效率，蓝色EQE可以显著增强，超过幅度上的单位。在蓝光偏置下，红色EQE仅在具有混合缓冲器的器件中增加。由于饱和的光电导性，它在CdS缓冲层中保持恒定，并且甚至由于蓝色光子通过更透明的In（2）S（3 i）n到吸收体的光学注入而在In 2S3缓冲层中降低。在白色照明下，增强可以观察到只有不饱和缓冲液，如In 2 S3和混合缓冲液，而红色EQE降低由于光注入。EQE中的这种光偏置依赖行为（包括EQE超过1）可以归因于两个关键因素：缓冲层的光电导性和吸收体的低少数载流子寿命。这种效应导致模拟器下测得的J（SC）与根据EQE积分计算的J（SC）之间的不一致，揭示了在验证它们之间的一致性时进行光偏压依赖性研究的必要性。在此基础上，提出了提高吸收层中少子寿命和缓冲层中多子浓度以提高器件电性能和性能的建议。
The light-bias-dependent behavior of external quantum efficiency (EQE) in kesterite Cu2ZnSnS4 solar cells utilizing different buffers has been reported. Under red light bias, the blue EQE can be enhanced significantly, exceeding unity in magnitude due to photoconductivity of buffers increasing 80 depletion region width and thereby increasing collection efficiency. Under blue light bias, the red EQE increases only in devices with a hybrid buffer. It stays constant with a CdS buffer due to saturated photoconductivity and even decreases with an In2S3 buffer due to optical injection of blue photons through the more transparent In(2)S(3 i)nto the absorber. Under white illumination, the enhancement can be observed only with unsaturated buffers such as In2S3 and the hybrid buffer, while the red EQE reduces due to optical injection. This light bias-dependent behavior in EQE (including EQE exceeding unity) can be attributed to two key factors: photoconductivity of the buffer layers combined with low minority carrier lifetime of absorber. The effect leads to disagreement between J(SC) measured under a simulator and that calculated from the integral of the EQE, revealing the necessity for light bias dependence investigation when verifying the consistency between them. Improving the minority carrier lifetime in absorber and majority carrier concentration in buffer to boost the device electrical property and performance is suggested based on this investigation.