Intrinsic quantum confinement in formamidinium lead triiodide perovskite

Adam D Wright (1) , George Volonakis (2, 1) , Juliane Borchert (1) , Christopher L Davies (1) , Feliciano Giustino (3, 1) , Michael B Johnston (1) , Laura M. Herz (1)

1 University of Oxford
2 ISCR - Institut des Sciences Chimiques de Rennes
3 University of Texas at Austin [Austin]

Understanding the electronic energy landscape in metal halide perovskites is essential for further improvements in their promising performance in thin-film photovoltaics. Here, we uncover the presence of above-bandgap oscillatory features in the absorption spectra of formamidinium lead triiodide thin films. We attribute these discrete features to intrinsically occurring quantum confinement effects, for which the related energies change with temperature according to the inverse square of the intrinsic lattice parameter, and with peak index in a quadratic manner. By determining the threshold film thickness at which the amplitude of the peaks is appreciably decreased, and through ab initio simulations of the absorption features, we estimate the length scale of confinement to be 10-20 nm. Such absorption peaks present a new and intriguing quantum electronic phenomenon in a nominally bulk semiconductor, offering intrinsic nanoscale optoelectronic properties without necessitating cumbersome additional processing steps.

Domaines: Chimie

Adam D Wright, George Volonakis, Juliane Borchert, Christopher L Davies, Feliciano Giustino, et al.. Intrinsic quantum confinement in formamidinium lead triiodide perovskite. Nature Materials, 2020, 19 (11), pp.1201-1206. ⟨10.1038/s41563-020-0774-9⟩. ⟨hal-02930358⟩