Fig. 2: Manipulating the exciton behavior and optoelectronic properties in (BA)2(GA)Pb2I7 by pressure-tuning.
a In situ steady-state PL spectra at selected pressures, where a remarkably enhanced emission with a more symmetric PL line shape is observed during compression, reaching the maximum at 2.1 GPa. b Symmetric factor and the relative PL intensity (in the logarithmic scale) as a function of pressure. The PL intensity reaches the maximum when the symmetric factor approaches 1. c The fitted exciton-phonon coupling strength (γLO) as a function of pressure. d Absorption spectra of an exfoliated (BA)2(GA)Pb2I7 single crystal at different pressures, where the gradually weakened excitonic absorption peak indicates the reduction of exciton binding energy Eb. e The exponential value α of carrier density dependent initial PL intensity (IPL at delay time t = 0 ps) as a function of pressure. The plot follows the law of \({I}_{{{\mbox{PL}}}}\left(t=0\right)\propto {\left({N}_{0}\right)}^{\alpha }\), and the α value indicates the major carrier specie (α = 1 implies excitons, α = 2 implies free carriers, and α between 1 and 2 suggests the coexisting of excitons and free carriers). f The photoconductivity at different pressures, where a significant 10-fold enhancement is achieved at 3.1 GPa. The inset shows a schematic illustration of the photocurrent measurement setup within a diamond anvil cell. Source data are provided as a Source Data file.
