CIGS薄膜太阳电池的数值模拟研究

Numerical Simulation of CIGS Thin-Film Solar Cells

摘要:

建立了铜铟镓硒(CIGS)薄膜太阳能电池结构模型,利用SCAPS模拟计算得到CIGS薄膜太阳能电池的载流子生成率、能带排列、电场强度等,研究了CIGS薄膜太阳能电池吸收层的Ga组分含量、不同共蒸法制备的电池吸收层缺陷密度、吸收层厚度、掺杂浓度对电池输出性能的影响。结果表明,单步共蒸法制备的电池中CIGS/CdS异质结“尖峰状”的能带排列有利于载流子传输；当Ga组分含量在30%时,太阳能电池的输出性能优异。三步共蒸法制备的电池吸收层缺陷密度进一步降低,可提升电池的输出性能。吸收层厚度为2.0μm厚的电池吸收层即可吸收大部分的光子,继续增加吸收层厚度会导致短路电流密度降低。增大吸收层掺杂浓度,提高了光生电动势、增大了开路电压,但CIGS/CdS异质结界面处势垒下降,载流子复合率上升,导致短路电流密度下降。优化CIGS薄膜太阳能电池参数后,利用SCAPS模拟得到其转换效率达到了27.67%。

Abstract:

This study investigates various copper-indium-gallium-selenium (CIGS) thin-film solar cells by adjusting the Ga component ratio, defect density, thickness, and doping concentration of the absorption layer in simulations using the SCAPS software. The results are correlated with the carrier generation rate, energy band alignment, and electric field. The simulations indicate that for a thin-film solar cell prepared via single-step co-evaporation, the energy-spike-like band alignment of the CIGS/CdS heterojunction facilitates carrier transport, resulting in excellent output performance when the Ga content is 30%. In contrast, the output performance of a solar cell prepared via three-step co-evaporation exceeds that of a solar cell prepared via single-step co-evaporation due to the lower defect density of its absorption layer. Increasing the thickness of the absorption layer causes the 2.0μm-thick layer to absorb most ultraviolet-visible light photons, but further increases decrease the short-circuit current density. Moreover, the open-circuit voltage and optovoltage of the solar cell increase with doping concentration, while the short-circuit current and potential barrier of the CIGS/CdS heterojunction decrease. By optimizing the thin-film solar-cell parameters, the photovoltaic conversion efficiency of the CIGS thin-film solar cell reached a maximum of 27.67%.