Modelling free-carrier absorption in solar cells

✍ Scribed by Donald A. Clugston; Paul A. Basore

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 209 KB
• Volume: 5
• Category: Article
• ISSN: 1062-7995
• DOI: 10.1002/(sici)1099-159x(199707/08)5:4<229::aid-pip164>3.0.co;2-6

✦ Synopsis

Free-carrier absorption can be a signi®cant parasitic optical absorption process in solar cells. Although estimates of its in¯uence have been made in the past, it has not previously been incorporated into a numerical semiconductor device simulator and studied in conjunction with other eects. A ®nite element model of free-carrier absorption is presented that incorporates the dependency of the absorption coecient on the carrier concentration pro®le, including the change in carrier density that occurs across a single ®nite element. This model has been implemented in the semiconductor modelling program PC1D for Windows, and used to simulate the eects of free-carrier absorption on several types of silicon solar cells. It was found to have only a very small eect on cell eciency, but can signi®cantly aect the longwavelength spectral response, which has implications for device characterization. Empirical equations for the behaviour of free-carrier absorption in a variety of materials are presented.