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Center for Nonlinear Studies |
Thanks to the intensive research efforts of a large scientific community over the past 7 years, lead (Pb)-based hybrid perovskite solar cells have achieved an impressive power conversion efficiency. Large improvements in the thermal and photo stability of this kind of solar cell by using more stable precursors, and robust hole/electron transport layers have been achieved. Despite these outstanding accomplishments, the toxicity of lead causes concerns about the possible large-scale utilization of this new type of solar cell. Among the various alternatives to lead, Sn has been recognized to have a great potential, as the Sn-based hybrid perovskites display excellent optical and electrical properties such as high absorption coefficients, small exciton binding energies and high charge carrier mobilities. In my talk I will show that Sn-based perovskites display evidences of photoluminescence from hot-carriers with unexpectedly long lifetime. The asymmetry of the PL spectrum at the high-energy edge, is accompanied by the unusually large blue shift of the time-integrated photoluminescence with increasing the excitation power. These phenomena are associated with slow hot carrier relaxation and state-filling of band edge states. I will further show all-tin-based hybrid perovskite solar cells with efficiencies of up to 9%. This record result is obtained with the addition of trace amount of 2D tin perovskite, which initiates the homogenous growth of highly crystalline and oriented FASnI3 grains at low temperature.
Host: Amanda Neurkirch