In recent years, lead halide perovskite nanocrystals (NCs) have emerged as excellent materials for light-harvesting applications.
1 These materials possess broad and intense absorption and
tuneable photoluminescence in the visible region of the electromagnetic spectrum. 2,3 The prime requirements for optimum performance in such NCs are: (a) ultrafast interfacial transfer of
photogenerated electrons (e-) and holes (h+); and (b) efficient transport of these charge carriers in the NCs. Charge transfer across interfaces is largely guided by the relative energy level alignments of the electron donor and acceptor moieties in the nanocrystals (NCs). Hence, factors like dimensionality, shape, size and chemical composition can influence the rate and efficiency of charge transfer in perovskite nanocrystals. 4 The seminar will highlight the current
understanding of charge carrier dynamics in lead halide-based perovskite NCs, using the results from ultrafast pump–probe spectroscopic studies, where the photo-induced transient states are
created using a pump laser, followed by probing the states by a broad-band optical pulse at different delay times (ranging from femto to nano seconds). In addition, the details of the current investigation involving charge transfer dynamics between colloidal CsPbBr3 NCs to a series of organic molecules will also be presented. The initial results from the study suggest that the rate of charge transfer from the perovskite NCs is directly proportional to the free energy change (-ΔG0) of the process, which in turn can be regulated by the choice of the organic acceptor molecules. Experimental details and future plan of the work will be discussed in the research proposal seminar.
References
1. W. Zhang, G. E. Eperon, H. J. Snaith, Nature energy, ,2016, 1, 1-8
2. L. Protesescu, S.Yakunin, M. I. Bodnarchuk, F. Krieg, R. Caputo, C. H. Hendon, R. X.
Yang, A. Walsh, M. V. Kovalenko, Nano Lett. 2015, 15, 3692−3696
3. M. V. Kovalenko, L. Protesescu, M. I. Bodnarchuk, Science, 2017, 358, 745−750
4. N. Mondal, A. De, S. Das, S. Paul, A. Samanta, Nanoscale, 2019, 11, 9796–9818