EXCITON LUMINESCENCE IN LEAD IODIDE LIFETIME, INTENSITY AND SPECTRAL POSITION DEPENDENCE ON TEMPERATURE

The emission spectrum of PbI2 on the low energy side of the fundamental exciton absorption, is studied in the temperature range 4.2°-180°K. An emission spectrum composed of many lines, is observed. The lines are interpreted as free exciton, bound exciton, and phonon assisted recombination lines. Temperature dependence of the position of the free exciton line is studied. The experimental results are shown to agree with the hypothesis of a lattice expansion effect at low temperatures and an electron-lattice interaction at higher temperatures. A very short luminescence lifetime (5.10-10sec) of the above lines is measured by the 'single photoelectron' technique. © 1969.