Measurement of Band Offsets and Shunt Resistance in CdTe Solar Cells Through Temperature and Intensity Dependence of Open Circuit Voltage and Photoluminescence

Journal Article · Fri Aug 02 04:00:00 EDT 2019 · Solar Energy

DOI:https://doi.org/10.1016/j.solener.2019.07.057· OSTI ID:1569453

Swartz, Craig H. ^[1]; Rab, Sadia R. ^[1]; Paul, Sanjoy ^[1]; Van Hest, Marinus F ^[2]; Dou, Benjia ^[2]; Luther, Joseph M ^[2]; Pach, Gregory ^[2]; Grice, Corey R. ^[3]; Li, Dengbing ^[3]; Bista, Sandip S. ^[3]; LeBlanc, Elizabeth G. ^[1]; Reese, Matthew O ^[2]; Holtz, Mark W. ^[1]; Myers, Thomas H. ^[1]; Yan, Yanfa ^[3]; Li, Jian V. ^[1]

---

1. Texas State University
2. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
3. University of Toledo

Band offsets at the back contact and front window layer in CdTe-based solar cells affect photovoltaic performance and challenge standard characterization methods. By analyzing the temperature and excitation dependence of both open circuit voltage and absolute photoluminescence intensity, we show that the effects band offsets can be separated from the effects of recombination and shunting. Solar cells were grown with MgZnO window layers and compared to cells with CdS window layers containing varying amounts of oxygen. It was demonstrated that band alignment rather than reduced recombination velocity is the reason for the success of MgZnO as a front interface contact. An assortment of thin back contact interlayers were also deposited, and a PbTe interlayer showed some promise as an Ohmic contact to the CdTe, though it appears to induce a photoconductive shunt. Finally, we show that the shunting resistance given by a standard current-voltage curve technique generally does not represent a physically meaningful quantity unless it is well below one kiloOhm square cm.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
• DOE Contract Number: AC36-08GO28308
• OSTI ID: 1569453
• Report Number(s): NREL/JA-5K00-75058
• Journal Information: Solar Energy, Journal Name: Solar Energy Vol. 189
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
contact barrier
injection dependence
loss analysis
model fitting
photovoltaic device characterization
recombination