Temperature dependence of the photocurrent excited above the fundamental absorption edge of PbWO₄

Abstract

Photocurrent of lead tungstate (PbWO 4 ) single crystals has been studied in the temperature range from 4 K to 270 K. The excitation spectrum of the photocurrent characterized by a prominent peak at 4.1 eV and a rise above 4.5 eV was obtained at 270 K. Below 150 K, the photocurrents excited at 4.15 eV and 4.7 eV show analogous temperature dependence with each others. However, the photocurrent excited at 4.15 eV exhibits thermal activation type temperature dependence above 150 K. We find that the photocurrent showing thermal activation is induced efficiently by the excitation at 4.12 eV, but by neither the excitonic transition nor the band-to-band transition. The temperature dependence of the photocurrent is discussed in terms of temperature dependence of the mobility and the carrier density.

Surfactant-Assisted Hydrothermal Synthesis, Physical Characterization, and Photoluminescence of PbWO4

“…They find that PbWO 4 crystals had a blue emission band at about 450 nm under the excitation line of 300 nm. As reported by Itoh et al, PbWO 4 crystals consist of two bands, “green luminescence” and “blue luminescence”. The “blue luminescence” is ascribed to the radiative recombination of a self-trapped exciton localized on a regular WO 4 complex anion, whereas the “green luminescence” is concluded to be extrinsic and may be a defect-related emission.…”

Exciton transition and electronic structure of PbMoO4 crystals studied by polarized light

“…The band gap energy of PbMoO 4 has not been unambiguously determined. In the case of PbWO 4 , it is estimated to be about 4.7 eV from the experiments of thermoluminescence 28 and photocurrent 29. This reveals that the exciton binding energy for the peak a 1 in PbWO 4 is about 0.4 eV.…”

Phase Transformation of Lead Tungstate at Normal Temperature from Tetragonal Structure to Monoclinic Structure

“…Even small changes in these conditions induce considerable changes of emission spectra . The “blue luminescence” is usually originated from a regular WO 4 2− complex anion, whereas the discussion about the “green luminescence” still remains controversial …”