Arsenic doped CdSeTe solar cells: Charge collection and Defects |
Niranjana Mohan Kumar1, Srisuda Rojsatien1, Trumann Walker1, Tara Nietzold1, Barry Lai2, Arun K.M. Kanakkithodi3, Maria Chan2, Dan Mao4, Mariana Bertoni1 1Arizona State University, Tempe, AZ, United States /2Argonne National Lab, Lemont, IL, United States /3Purdue University, West Lafayette, IN, United States /4First Solar, Perrysburg, OH, United States |
The selection of arsenic as a dopant has been an integral part of achieving high performing, 20.8%, polycrystalline CdTe solar cells. Although arsenic has significantly improved the long-term performance of the cells and the p-type doping levels reached inside the absorber, the activation ratio of dopant remains quite low, ~1%. Understanding the origins of this activation would aid in further bettering device performance. Herein, devices of two different activation levels but identical arsenic concentration are studied using nanoscale correlative X-ray microscopy in cross-section. Charge collection in cross-section shows a distinctive change between activation levels and the local environment around the As atom, as measured by X-ray absorption, shows the signature of several defects and phases that could be the culprit. |