Mesoscale Functional Imaging of Materials for Photovoltaics

Further global adoption of photovoltaic energy conversion technologies is contingent on sustained progress toward widespread grid-parity. For that, solar cell materials composed of microscale grains and nanoscale boundaries show the highest potential due to their large theoretical efficiency and low-cost fabrication methods. Here we outline the current challenges facing hybrid perovskites and prevalent thin-film polycrystalline materials for photovoltaics. We offer our perspective on how mesoscale functional imaging can enable a complete understanding of the physical and chemical processes restricting their performance, completing the materials science structure-properties processing-performance tetrahedron. First, we present the key characteristics of hybrid perovskites, CdTe, CIGS, CZTS, and pc-GaAs, emphasizing their main limitations. Second, we discuss how novel imaging methods based on electron and scanning probe microscopies can be realized to provide quantitative information about the relevant parameters (figures-of-merit) that define solar cell performance, with nanoscale spatial resolution. Finally, we offer our vision for the upcoming years, wherein correlative functional microscopy will lead to a complete narrative of the electrical, optical, structural, and chemical properties of these materials, including their surface and bulk properties.