Performance Comparison of CdTe:Na, CdTe:As, and CdTe:P Single Crystals for Solar Cell Applications

• Published in: Materials 2022-02, Vol.15 (4), p.1408
• Main Authors: Kim, Sangsu, Kim, Deok, Hong, Jinki, Elmughrabi, Abdallah, Melis, Alima, Yeom, Jung-Yeol, Park, Chansun, Cho, Shinhaeng
• Format: Article
• Language: English
• Subjects: Annealing; Arsenic; Bridgman method; Cadmium tellurides; Carrier lifetime; Circuits; Crystal growth; Dopants; Efficiency; Hole density; Interfacial properties; Lifetime; Minority carriers; Open circuit voltage; Phosphorus; Photovoltaic cells; Short circuit currents; Single crystals; Sodium; Solar cells; Space missions; Thermal stability; Thermal stress
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma15041408

We compared thermal stability, open-circuit voltage, short-circuit current, and fill factor values of single-crystal Cadmium telluride (CdTe) grown using the vertical Bridgman (VB) technique and doped with group V elements (phosphorus and arsenic), and group Ⅰ element (sodium), followed by an annealing process. The sodium-doped CdTe maintained a hole density of 10 cm or higher; after annealing for a long time, this decreased to 10 cm or less. The arsenic-doped CdTe maintained a hole density of approximately 10 cm even after the annealing process; however its bulk minority carrier lifetime decreased by approximately 10%. The phosphorus-doped CdTe maintained its properties after the annealing process, ultimately achieving a hole density of ~10 cm and a minority carrier lifetime of ~40 ns. The characteristics of a single-crystal solar cell were evaluated using a solar cell device that contained single-crystal CdTe with various dopants. The sodium-doped sample exhibited poor interfacial properties, and its performance decreased rapidly during annealing. The samples doped with group V elements exhibited stable characteristics even during long-term annealing. We concluded, therefore, that group V elements dopants are more suitable for CdTe single-crystal-based solar cell applications involving thermal stress conditions, such as space missions or extreme fabrication temperature environments.