Temperature dependence of photoconversion efficiency in silicon heterojunction solar cells: Theory vs experiment
Silicon heterojunction solar cells (HJSC) with the efficiency of about 20% are manufactured. Their short circuit current, open circuit voltage, photoconversion efficiency, and fill factor of the current voltage curve are measured in a broad temperature range from 80 to 420 K. It is established that the open circuit voltage, the fill factor, and the photoconversion efficiency are non monotonic functions of temperature, having a maximum in the vicinity of 200 K. A new approach to modeling of HJSCs is proposed, which allows one to obtain quantitative agreement with the experimental results at temperatures above 200 K, as well as to describe the results published in the literature on the solar cells under AM1.5 conditions. The temperature coefficient of photoconversion efficiency in HJSCs is discussed, and its low value is shown to be related to the low surface and volume recombination rates. Finally, a theoretical expression for the SC's temperature under natural working conditions is derived.