Optical absorption studies on gel grown single crystals and vacuum evaporated thin film of lead iodide have been carried out at room temperature and liquid nitrogen temperature.The exciton peak in the case of gel grown crystal was observed at 4940 A whereas for the film at 4900 A. The presence of lead colloids in the film was revealed through a broad featureless band around 5500 A. The absorption tails in the temperature range from 80 to 300 K are found t o obey Urbach rule. Examining the various power law dependences of the observed optical density on photon energy, it has been established that the transition is of direct type resulting in a band gap of 2.53 ev.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.