Perovskite metal halides, represented by CH3NH3PbI3, have yielded unprecedented advances in photovoltaics with power conversion efficiencies close to 20%, rivaling the performance of industry standard silicon. The excellent electronic properties, especially the balanced electron and hole diffusion lengths, has positioned this material at the forefront of solution processed photovoltaics, as well as an excellent candidate for light emission and lasing applications. Most of the recent improvements of devices based on perovskites have pursued the pathway of new device architectures and on incremental improvements of the fabrication processes. Although these strategies have yielded success, it is essential to expand the family with new materials that can match the advantages of CH3NH3PbI3 and address some of its drawbacks, such as moisture stability and toxicity. Although alternatives to methyl ammonium lead halide with substitutions of the organic cation with formamidinium or caesium, lead with tin, and halide substitutions are beginning to be investigated; there are clear indications that these represent only the beginning of the perovskite era. It is possible to prepare a large variety of 0, 1, 2, 3-D hybrid organic-inorganic structures with potentially important technological properties. The layered 2-D systems (A2MX4) can accommodate much larger and more complex organic cations and thus offers a greater control over their structural and physical properties. Whereas, the 0 & 1-D systems synthesised via manipulation of the organic and inorganic components would yield critical control of the photovoltaics and light emission properties. This presentation will address the various challenges and opportunities in perovskite solar cells beyond methyl ammonium lead iodide with particular emphasis on their optoelectronic properties.
Subodh Mhaisalkar is the Tan Chin Tuan Centennial Professor in the School of Materials Science & Engineering at the Nanyang Technological University (NTU), Singapore. Subodh is also the Executive Director of the Energy Research Institute @ NTU (ERI@N), a panUniversity multidisciplinary research institute for innovative energy solutions. Prior to joining NTU in 2001, Subodh has over 10 years of research and engineering experience in the microelectronics industry and his areas of expertise and research interests includes semiconductor technology, perovskite solar cells, printed electronics, and energy storage. Subodh received his Bachelors’ degree from IIT-Bombay and his MS/Ph.D. degrees from The Ohio State University.