Non-epitaxial carrier selective contacts for III-V solar cells: A review

In the last few years, carrier selective contacts have emerged as a means to reduce the complexities and losses associated with conventional doped p-n junction solar cells. Still, this topic of research is only at its infancy for III-V solar cells, in comparison to other solar cell materials such as silicon, perovskites, chalcogenides, etc. This could be because high quality III-V solar cell materials can be achieved relatively easily using epitaxial growth techniques such as MOCVD (metal organic chemical vapor deposition) and MBE (molecular-beam epitaxy). However, current epitaxial III-V solar cells are very expensive and cannot compete for the terrestrial market, and therefore, researchers are developing alternative growth methods such as thin-film vapor–liquid–solid (TF-VLS), hydride vapor phase epitaxy (HVPE) and closed space vapor transport (CSVT), which are significantly lower in cost compared to epitaxial III-V solar cells. However, at present, these relatively nascent low cost growth methods, face severe optimization issues when it comes to growth of controlled p-n junction, along with heavily doped window and back surface field layers. In such cases, carrier selective contacts can be hugely beneficial. In this review, we cover some of the most recent research on the use of carrier selective contacts for III-V solar cells. Future prospects, challenges, and new device concepts using carrier selective contacts will also be discussed.