Progress in tailoring perovskite based solar cells through compositional engineering: Materials properties, photovoltaic performance and critical issues

Since the discovery of perovskite based solar cells in 2009 followed by breakthroughs at Oxford in 2012, continuous efforts by the scientific community have led to tremendous developments in perovskite solar cells (PSCs) which is perhaps the most promising recent solar photovoltaic (PV) and energy harvesting technology. Advancements in nanotechnology and availability of better infrastructures for PSCs research have accelerated this field leading to the dramatic rise in efficiency with expectations of commercialization soon. Amongst other solar cell devices, PSCs have demonstrated record efficiencies exceeding 22% off late in just a few years establishing as the fastest growing solar PV technology. This extremely rapid progress in PSCs is not only because of unique properties of perovskite materials in the devices but also due to engineering and modification of other components as well as device architecture facilitating the conducive microstructure and interfaces to result in higher power conversion efficiencies. These other components such as electron transport materials (ETMs) and hole transport materials (HTMs) not only play a vital role in determining the device efficiency but also the stability of PSCs. This review focuses on the recent investigations carried out to achieve high performance and long term stability of PSCs, with primarily focus on doping or composition engineering of various components of PSCs devices (perovskite, ETM and HTM) resulting in enhanced properties with respect to their role in delivering high performance PSCs. Although, a great deal of research has been carried out and reviewed on PSCs, investigations correlating material compositions and properties vis-a-vis increase in the efficiency and enhancement in the stability, although very interesting, are rarely reviewed. Hence, this review focuses on the recent developments and critical issues related to microstructure, properties and stability of the devices resulting from doping or composition engineering. In this article, first a basic introduction to PSCs and perovskite as materials for PV devices is followed by the role and importance of ETM and HTM. The article further reviews in-detail about doping and compositional engineering in ETM, HTM and perovskite material in order to improve the PSC device performance. Finally, the article will provide an outlook towards various issues requiring further attention which can help in eventually facilitating technological promise of PSCs. (C) 2018 Elsevier Ltd. All rights reserved.