Microstructures and optical properties of porous PbSe film prepared by ion exchange process

Abstract

PbSe films can be widely applied in many fields involving industrial temperature measurement, military guidance, agriculture detection and celestial observation due to their high reliability and sensitivity. The porous PbSe film with a grain size of ∼0.5 μm was firstly transformed from flaky pastry-like plumbonacrite (Pb10O(OH)6(CO3)6) precursor film by ion exchange process, where the precursor film was prepared by a low-toxicity chemical bath deposition (CBD) process. The variations of phase composition, surface morphology, and binding state of main surface elements, as well as the optical properties of films with immersion time were mainly investigated. The experimental results show that the flaky pastry-like Pb10O(OH)6(CO3)6 film can be fully converted to cubic PbSe film as the immersion time is over 1.5 h, and the grain size of PbSe is further increased with the immersion time prolonging from 1.5 to 2.5 h. Moreover, the presence of a large number of pores in PbSe film can produce low reflectance, leading to the improvement of optical performance of PbSe film in the infrared wavelength range. The XPS, Raman and TEM analyses demonstrate the presence of trace impurities and lattice defects, which can be related to the oxidation, incomplete transformation and mutual extrusion between grains. The calculated bandgap is decreased from 2.68 eV for Pb10O(OH)6(CO3)6 film to 0.39 eV for PbSe film.