20%-efficient polycrystalline Cd(Se,Te) thin-film solar cells with compositional gradient near the front junction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 36543763.
- Also identified by DOI 10.1038/s41467-022-35442-8 and PMC identifier 9772316.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Bandgap gradient is a proven approach for improving the open-circuit voltages (V<sub>OC</sub>s) in Cu(In,Ga)Se<sub>2</sub> and Cu(Zn,Sn)Se<sub>2</sub> thin-film solar cells, but has not been realized in Cd(Se,Te) thin-film solar cells, a leading thin-film solar cell technology in the photovoltaic market. Here, we demonstrate the realization of a bandgap gradient in Cd(Se,Te) thin-film solar cells by introducing a Cd(O,S,Se,Te) region with the same crystal structure of the absorber near the front junction. The formation of such a region is enabled by incorporating oxygenated CdS and CdSe layers. We show that the introduction of the bandgap gradient reduces the hole density in the front junction region and introduces a small spike in the band alignment between this and the absorber regions, effectively suppressing the nonradiative recombination therein and leading to improved V<sub>OC</sub>s in Cd(Se,Te) solar cells using commercial SnO<sub>2</sub> buffers. A champion device achieves an efficiency of 20.03% with a V<sub>OC</sub> of 0.863 V.