Optical and Electrical Characterization of Nanocrystalline (Pb1Xbi) S Thin Films Deposited at Room TempratureIn this paper, nanocrystalline (Pb1-xBix)S thin films were successfully deposited on suitably cleaned glass substrate at constant room temperature, using the chemical bath deposition technique. The deposited films were further annealed at 4000 C in air. The optical characterization of the films was done by optical absorption and transmission spectra in the range 400-1100 nm using UV spectrophotometer. The band gap of the films was found to be in the range 1.6-2.2 eV for x = 0 to 0.05. The room temperature electrical resistivity of the synthesized films was measured by photoconductivity measurement unit. On increasing Bi doping concentration, electrical conductivity decreases.The synthesis and characterization of semiconductor nanoparticles is an exciting field of research for future applications in optoelectronics [1, 2]. Nanostructured materials and in particular semiconductor nanostructures and thin films may be exploited for their novel electronic and optical properties. These structures are of great interest since they have potential applications in future quantum and photoinic devices . Lead chalcogenides have been the subject of considerable research due to their technological importance in crystalline and polycrystalline forms. PbS is an attractive semiconductor material that exhibits strong size quantization effects due to the high dielectric constant and the small effective mass of electron and holes, suggesting that its band gap energy can be easily manipulated from the bulk value (0.41 eV) to a few electron volts by the changes in the material’s size [4-6]. This material has also been used in many fields such as infrared photography, diode laser, humidity and temperature sensors, and decorative and solar control coatings among other applications . Novel materials are needed for thin film solar cells apart from the most extensively studied material CdTe and CuInSe2. PbS thin films have excellent solar control characteristics . Nanocrystalline PbS materials are novel materials, and their properties are different and often superior to those of conventional coarse-grained materials. The absorption edge has been found to be blue shifted as particle size reduced. . Also polycrystalline PbS thin films show good photoconductive properties . Many methods have been developed to synthesize Pbs thin films, including vaccum deposition , electrochemical deposition , chemical bath deposition (CBD) , pulsed laser deposition , and, spray pyrolysis . Among those deposition techniques, chemical bath deposition (CBD) is the convenient and frequently used deposition technique to grow good quality thin films. On account of the various applications of these films, an attempt has been made to deposit nanocrystalline (Pb1-xBix)S thin film using the CBD method and to investigate the optical and electrical properties of these films.Rajesh Kumar et. al.