Our search for sustainable energy generation technology has led researchers to investigate various materials and their combinations in many types of devices. One such synthetic material is called "perovskite," which is low-cost and easy to produce, and can be used in solar cells. Perovskite solar cells have attracted much attention because their power conversion efficiency (that is, their efficiency at turning sunlight into electricity) has seen dramatic improvements in recent years. However, it has proven difficult to implement them for large-scale energy generation because of a handful of issues.
One problem that perovskite solar cells face is reproducibility. This means that it is hard to consistently create perovskite crystal layers free of defects and holes, which means that deviations from design values are always likely to occur, which reduce their efficiency. On the bright side, researchers have found that the efficiency of these cells can be boosted by combining perovskite with carbon nanotubes (CNTs). The mechanism by which CNTs and perovskite bond together and how this affects the performance of CNT perovskite solar cells has not been studied in depth. In particular, the ability of pure CNTs to bond to perovskite is not very good, and this could compromise the structural and conducting properties at the interface of both materials.
Hence, a team from Tokyo Tech lead by Prof. Keiko Waki conducted a series of experiments on perovskite solar cells combined with different types of CNTs in an attempt to both improve their performance and stability and understand the underlying mechanisms. They used not just pure CNTs, but also CNTs that bore "oxygen-containing functional groups" in their structure, which have been known to strengthen the interaction between the CNTs and perovskite, resulting in better interfaces and enhancing the crystallization of perovskite.To read more, click here.