Rapid thermal evaporation used to deposit CdSe thin films
CdSe films demonstrated high crystal quality with large grain size and preferred crystal orientation suitable for solar cells
CdSe has great potential in the application of Si-based tandem solar cells because of the suitable bandgap of ~1.7 eV, excellent optoelectronic properties, high stability, and low manufacturing cost. Nevertheless, the progress of CdSe thin-film solar cells has been slow, and there are few systematic studies on CdSe thin-film solar cells in recent years.
Now a team from Wuhan National Laboratory for Optoelectronics (WNLO), the China-EU Institute for Clean and Renewable Energy (ICARE), and the State Research Institute, Center for Physical Sciences and Technology, Lithuania have proposed a method of rapid thermal evaporation (RTE) to obtain high-quality CdSe thin films and designed CdSe thin-film solar cells. This study entitled “Rapid thermal evaporation for cadmium selenide thin-film solar cells” was published in Frontiers of Optoelectronics on Dec. 6, 2021.
In this study, the RTE was employed to deposit CdSe thin films, which demonstrate high crystal quality with large grain size and preferred crystal orientation. Meanwhile, the sharp absorption edge at 720 nm indicates CdSe thin film with a direct bandgap of 1.72 eV.
The strong photoluminescence with full width at half maximum of 23 nm reveals the CdSe thin films with relatively few defects. Based on the high-quality CdSe thin films, suitable electron transport layer (ETL) and hole transport layer (HTL) were introduced to construct CdSe solar cells. Finally, an efficiency of 1.88 percent was achieved by designing an optimal configuration of FTO/ZnO/CdS/CdSe/PEDOT/CuI.
This study developed, for the first time, a RTE method to deposit CdSe thin films and provided a systematical characterisation of the optoelectric properties. Also, it demonstrated general rules for device design and optimisation for CdSe solar cells. It also pointed out the advantages of CdSe thin film and its solar cells. In the future, CdSe solar cells are of high potential in Si-based tandem applications, which is worthy of further study.
