Emitter Choice for Epitaxial CdTe Solar Cells
High-quality epitaxial CdTe layers with low defect density and high carrier concentration have been demonstrated by several research groups. Nevertheless, one primary challenge for high-performance epitaxial CdTe solar cells is how to choose a suitable emitter partner for the junction formation. The numerical simulations show that a type I heterojunction with small conduction band offset (0.1 eV = ..delta..Ec = 0.3 eV) is necessary to maintain a good cell efficiency even with large interface recombination. Otherwise, a small 'cliff' can assist interface recombination causing smaller Voc, and a large 'spike' (..delta..Ec = 0.4 eV) can impede the photo current and lead to a reduction of JSC and FF. Among the three possible emitters, CdS, CdMgTe, and MgZnO, CdMgTe (with ~30% Mg) and MgZnO (with ~ 20% Mg) are likely to be a better choice since their type-I junction can tolerate a larger density of interface defects.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S), SunShot Initiative
- DOE Contract Number:
- AC36-08GO28308
- OSTI ID:
- 1344214
- Report Number(s):
- NREL/CP-5K00-67984
- Resource Relation:
- Conference: Presented at the 2016 IEEE 43rd Photovoltaic Specialists Conference (PVSC), 5-10 June 2016, Portland, Oregon
- Country of Publication:
- United States
- Language:
- English
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