Establishing the Limits of Efficiency of Perovskite Solar CellsNovember 16, 2016
Fig. 1(a): Composition of perovskites under consideration (in the organic cation, blue = N, black = C, white = H).
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The recent surge in research on metal-halide-perovskite solar cells has led to a seven-fold increase of efficiency, from ~3% in early devices to over 22% in research prototypes. Oft-cited reasons for this increase are: (i) a carrier diffusion length reaching hundreds of microns; (ii) a low exciton binding energy; and (iii) a high optical absorption coefficient. These hybrid organic-inorganic materials span a large chemical space with the perovskite structure. In a recent article in Scientific Reports, Prof. Efthimios Kaxiras and colleagues establish, using first-principles calculations and thermodynamic modelling, that, given the range of band-gaps of the metal-halide-perovskites, the theoretical maximum efficiency limit is in the range of ~25–27%. Their conclusions are based on the effect of level alignment between the perovskite absorber layer and carrier-transporting materials on the performance of the solar cell as a whole. These results provide a useful framework for experimental searches toward more efficient devices.
See Oscar Grånäs, Dmitry Vinichenko & Efthimios Kaxiras, "Establishing the limits of efficiency of perovskite solar cells from first principles modeling," Scientific Reports 6: 36108 (2016) doi:10.1038/srep36108.