LAUSR

The replacement of fossil fuel-based technologies still requires an effective high-efficiency and low-cost photovoltaic (PV) technology. According to the National Renewable Energy Laboratory (NREL) Renewable Electricity Futures Study, 80% of the power generated in the US could be from renewable sources by 2050 [1], which requires that PV electricity generation increases to >10%. Yet, only 1% of the electricity is generated by solar power today [2]. The current high cost/Watt, $5.3/W for <10kW systems, is still the main challenge to achieve NREL’s target. Perovskites and thin-film polycrystalline materials are a potential alternative for low-cost PV, but improvement in efficiency is required to ensure low cost/W. The performance of the best solar cells is still limited by the open-circuit voltage (Voc), the maximum voltage available from a PV device, which is related to the radiative recombination (photon emission) within the material. The Voc of both well-established and emerging materials is considerably below theoretical predictions [3]. This work addresses this critical limiting factor that constrains perovskite and thin-film polycrystalline solar cells’ performance. While macroscopic light currentvoltage (I-V) measurements are useful for determining the overall device performance, a nanoscale imaging spectroscopy method to spatially resolve the local optical and electrical properties to access charge carrier recombination processes within materials for PV is crucial for understanding inefficiencies [4,5].