Compositional and Interfacial Engineering for Highly Efficient Perovskite Solar Cells with Extremely Low Voltage Loss

Organic-inorganic metal halide perovskite solar cells (PVSCs) have attracted tremendous attention from various scientific communities due to their superb semiconducting properties. Very recently, the power conversion efficiency (PCE) has realized a certified value of 23.3%. Further improvement of the PCE has been greatly limited by the open-circuit voltage, since the reported short-circuit current density has reached over 90% of the theoretical Shockley-Queisser (S-Q) limit while the open-circuit voltage only received much less than 90% of the limit. Various approaches have been carried out to reduce voltage loss. However, the deep understanding of the voltage loss and the in-depth mechanism are still lacking. In our project, we aim to address voltage loss originally through designing perovskite absorber and the adjacent interfaces. Integrated characterization of both materials and devices will be performed to deeply investigate the dependence of voltage loss on the compositions and interfaces, as well as provide a broad rule for the control of voltage loss. The PI has accumulated broad expertise of perovskite photovoltaics in the past 7 years’ research, including the crystallography of hybrid perovskites, material processing and interface engineering as well as advanced optoelectronic characterizations. To alleviate the voltage loss and unveil the relevant mechanism in optoelectronic devices, we proposed the following tasks: (1) from the perspective of materials, we will design novel perovskite materials through composition engineering and microstructure control; (2) from the perspective of interfaces, we will tune the interfacial properties by surface modifications and development of novel charge transport layers (CTLs); (3) by integrating perovskite and its interfaces, we will investigate and explore how the perovskite and perovskite/CTLs interfaces contribute to device performance and voltage loss, and establish the structure-properties-performance relationship. Our preliminary results have obtained a very low voltage loss of 420 mV in high-performance PVSCs, close to 370 mV of monocrystalline silicon photovoltaics, elucidating the high feasibility of our proposed work. We believe that the implementation of this proposal could not only explore and unveil the relationship between materials design/interfacial modification and optoelectronic performance, but also provide a new route to develop high quality perovskite absorber and CTLs to realize highly efficient and reliable PVSCs with extremely low voltage loss for mass production and commercialization. The technology developed through our comprehensive characterization and analysis in this project would also help establish more reliable characterization protocols in the photovoltaics field.