Fig. 3
From: Scaling law for excitons in 2D perovskite quantum wells
Optical spectroscopy of the RPP crystals with n equals 1 to 5. a Experimental optical bandgap scaling. b Photoluminescence spectra. c Schematics of the Rydberg series of the exciton ground state (1s) and excited exciton states (2s, 3s, etc.) merging with the continuum. (Right) Corresponding absorption or optical density, photoluminescence PL, and photoluminescence excitation PLE spectra typically observed in 2D material systems26,49. d Optical density OD and e PLE spectra of the RPPs with n equals 1 to 5, respectively. Stars point to exciton ground state optical transitions, black squares show the continuum onsets and gray brackets indicate the region of excited exciton states. Labels A, B and C indicate absorption regions at energies higher than the continuum bandgap EG and which are apparently common to all the RPPs given an energy shift proportional to the bandgap
