Pressure induced emergence of visible luminescence in : Effect of structural distortion in optical behaviour

D Samanta, P Saha, B Ghosh, SP Chaudhury… - arXiv preprint arXiv …, 2020 - arxiv.org
D Samanta, P Saha, B Ghosh, SP Chaudhury, S Bhattacharya, S Chatterjee, GD Mukherjee
arXiv preprint arXiv:2009.01478, 2020arxiv.org
We report emergence of photoluminescence at room temperature in trigonal $
Cs_3Bi_2Br_9 $ at high pressures. Enhancement in intensity with pressure is found to be
driven by increase in distortion of $ BiBr_6 $ octahedra and iso-structural transitions.
Electronic band structure calculations show the sample in the high pressure phase to be an
indirect band gap semiconductor. The luminescence peak profile show signatures related to
the recombination of free and self trapped excitons, respectively. Blue shift of the both peaks …
We report emergence of photoluminescence at room temperature in trigonal at high pressures. Enhancement in intensity with pressure is found to be driven by increase in distortion of octahedra and iso-structural transitions. Electronic band structure calculations show the sample in the high pressure phase to be an indirect band gap semiconductor. The luminescence peak profile show signatures related to the recombination of free and self trapped excitons, respectively. Blue shift of the both peaks till about 4.4 GPa are due to the exciton recombination before relaxation due to the decrease in exciton lifetime with scattering from phonons
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