Light- and Elevated-Temperature-Induced Degradation-Affected Silicon Cells From a Utility-Scale Photovoltaic System Characterized by Deep-Level Transient Spectroscopy

作者：Steve Johnston, Chuanxiao Xiao, Michael G. Deceglie, E. Ashley Gaulding, Chun‐Sheng Jiang, Harvey Guthrey, Dana B. Kern, George F. Kroeger, Mowafak Al‐Jassim, Ingrid Repins · 发表于：IEEE Journal of Photovoltaics · 年份：2022 · DOI：10.1109/jphotov.2022.3158545 · 被引用次数：10 · 研究领域：Silicon and Solar Cell Technologies、Thin-Film Transistor Technologies、Photovoltaic System Optimization Techniques

Photovoltaic modules from a utility-scale field experienced power loss by light- and elevated-temperature-induced degradation (LeTID). Samples from the affected monocrystalline silicon cells are cored and extracted from the module packaging and then laser-scribed to form 2-mm diameter isolated areas. Using deep-level transient spectroscopy, a majority-carrier, hole-trap defect with an activation energy of 0.42 eV is detected on degraded and regenerated samples. The LeTID-degraded sample, however, has a larger signal corresponding to a trap density of 1.1 × 1013cm−3, which is about five times larger than the 2.1 × 1012cm−3trap density of the regenerated sample. An increase in filling pulse time from 50μs to 20 ms shows a slight decrease in activation energy from 0.42 to 0.36 eV suggesting that the defect level may consist of a band of energy states where shallower states continue to fill with long filling times. The capture rate of the defect is directly measured using an increasing series of filling pulsewidths in 15 to 125 ns range. This leads to a measured capture cross section of 5.1 × 10−17cm2, and using an approximate defect density of 1013cm−3, the majority-carrier-hole lifetime related to this defect is approximately 100μs when in the LeTID-degraded state.