Optoelectronic properties and stability of next-generation perovskite materials for solar cells

Organic-inorganic metal halide perovskites (ABX3 stoichiometry) have made a remarkably successful entry into the field of next-generation photovoltaic cells. A rapidly intensifying research activity has since led to certified power conversion efficiencies now exceeding 25% for single-junction thin-film solar cells. While competing technologies currently exist for such devices, the world's growing need for energy supply, lighting and display technologies has created an increasing desire for low-cost, high-efficiency solutions. Continued advances in photovoltaic devices, in particular, are urgently required to address climate change and energy security, which are arguably the greatest challenges to be faced by mankind over the coming century.

This Industrial CASE Studentship will focus on critical issues remaining to be resolved regarding the optoelectronic performance and stability of metal halide perovskites.

Factors that influence the efficient operation of perovskite solar cells will be elucidated, including mechanisms for electron-phonon coupling, charge-carrier mobility and recombination, light emission and re-absorption. In addition, the stability of these materials will be enhanced through critical examination of factors such as ionic migration and chemical conversion, e.g. under atmospheric conditions. Fundamental photon-to-charge conversion processes will be explored using a combination of ultra-fast optical techniques, e.g. transient absorption, photoluminescence up-conversion and THz pump-probe spectroscopy, while chemical conversions and material instabilities will be examined with x-ray diffraction and electron microscopies. These studies will feed directly into collaborative efforts aimed at propelling forward the creation of commercially available perovskite solar cells, addressing stability, band-gap tunability, lead-free perovskites, trap-free materials, material morphology control and multi-junction device structures. The project will benefit from the complementary expertise of Prof Herz's group at the University of Oxford on fundamental materials analysis, and of the project partner, Oxford Photovoltaics, who are leaders in perovskite solar technology and are currently exploring their use, for example, integrated in tandem with standard silicon solar cells.

The proposed research clearly fits within the EPSRC's portfolio, targeting identified Grand Challenges in Physics (Nanoscale Design of Functional Materials) and Chemistry (Directed Assembly of Extended Structures with Targeted Properties). The proposed programme also clearly falls into the EPSRC Themes of Physical Sciences, Energy & Manufacturing the Future; and the Areas of Materials for Energy Applications, Computational and Theoretical Chemistry and Solar Technology.