Fig. 4: Size-dependent single-photon superabsorption in CsPbBr3 QD thin films.
From: Single-photon superabsorption in CsPbBr3 perovskite quantum dots
a, Experimental absorbance spectra of QD thin films at 15 K for mean QD sizes of 3.5 nm, 5 nm, 7 nm, 17 nm and 30 nm; the energy scale (E – E1S) is referenced to the respective bandgap E1S, the absorbance is normalized to the 1S peak, and the 1S and 1P peaks are indicated with labels. b, Experimental size-dependent energy separation ΔE1S1P between the 1S and 1P transition (markers) coarsely follows the trend based on a simple particle-in-a-box model (solid line); the QD size is expressed in multiples of the Bohr cube volume (VQD/VBohr), assuming a Bohr radius of 3.1 nm. c, With increasing QD size, the 1S–1P absorbance ratio A1S/A1P at 15 K (markers) increases by about one order of magnitude; QDs lacking electronic correlation would exhibit a much weaker and size-independent A1S/A1P ratio close to the associated degeneracy ratio, that is, 1/3 (dashed horizontal line); after including electronic correlation effects, CI-EMA calculations (solid line) quantitatively reproduce the experimental trend.
