[论文解读] Accelerated development of CuSbS2 thin film photovoltaic device prototypes

Adam W. Welch, Lauryn L. Baranowski+6 more|arXiv (Cornell University)|Apr 6, 2015

Chalcogenide Semiconductor Thin Films参考文献 18被引用 9

一句话总结

本研究通过在三步自调控生长过程中应用高通量组合方法，加速了CuSbS2薄膜太阳能电池的开发。该方法实现了对吸收层相纯度、晶体取向、厚度及背接触的系统优化，获得了初始器件原型，其功率转换效率约为1%，受限于电流收集效率低下以及CuSbS2/CdS界面处的悬崖型导带偏移。

ABSTRACT

Development of alternative thin film photovoltaic technologies is an important research topic due to the potential for low-cost, large-scale fabrication of high-efficiency solar cells. Despite the large number of promising alternative absorbers and corresponding contacts, the rate of progress is limited by complications that arise during solar cell fabrication. One potential solution to this problem is the high-throughput combinatorial method, which has been extensively used for research and development of individual absorber and contact materials. Here, we demonstrate an accelerated approach to development of thin film photovoltaic device prototypes based on the novel CuSbS2 absorber, using the device architecture employed for CuInxGa(1-x)Se2 (CIGS). The newly developed three-stage, self-regulated CuSbS2 growth process enables the study of PV device performance trends as a function of phase purity, crystallographic orientation, layer thickness of the absorber, and numerous back contacts. This exploration results in initial CuSbS2 device prototypes with ~1% conversion efficiency; currently limited by low short-circuit current due to poor collection of photoexcited electrons, and a small open-circuit voltage due to a cliff-type conduction band offset at the CuSbS2/CdS interface (suggested by first-principles calculations). Overall, these results illustrate the potential of combinatorial methods to accelerate the development of thin film photovoltaic devices with novel absorbers.

研究动机与目标

• 加速基于新型CuSbS2吸收层材料的薄膜光伏器件的开发。
• 通过将高通量组合方法应用于器件结构，克服新型吸收层集成进展缓慢的问题。
• 系统探究相纯度、晶体取向、吸收层厚度及背接触材料对器件性能的影响。
• 结合第一性原理计算与实验数据，识别早期阶段CuSbS2器件的关键性能限制因素。

提出的方法

• 采用三步自调控CuSbS2生长工艺，以控制相纯度和晶体取向。
• 应用组合方法，在单个基底上并行改变吸收层厚度和背接触材料。
• 以成熟的CIGS器件结构为模板进行器件制备与测试。
• 开展高通量电学与结构表征，绘制不同组分与工艺参数下的性能趋势图。
• 通过第一性原理计算分析CuSbS2/CdS界面处的导带偏移。
• 将实验结果与理论预测相结合，指导器件结构的优化。

实验结果

研究问题

• RQ1 CuSbS2的相纯度如何影响薄膜器件中的光伏性能？
• RQ2 晶体取向与吸收层厚度对器件效率及电流收集有何影响？
• RQ3 不同背接触材料如何影响器件性能与界面特性？
• RQ4 CuSbS2/异质结界面处的导带偏移在多大程度上限制了开路电压？
• RQ5 高通量组合方法能否显著加速新型薄膜光伏原型的开发？

主要发现

• 初始的CuSbS2器件原型实现了约1%的功率转换效率。
• 短路电流偏低归因于吸收层中光激发电子的收集效率低下。
• 在CuSbS2/CdS界面处发现的悬崖型导带偏移是导致开路电压低下的主要原因。
• 第一性原理计算证实了显著的能带偏移存在，阻碍了电子的提取。
• 三步自调控生长工艺实现了对相纯度与晶体取向纹理的可重复控制。
• 组合方法在快速识别早期器件开发中的性能趋势与关键限制方面表现出显著有效性。