Effect of TEA on photoluminescence properties of PbS nanocrystalline thin films

Abstract

In this work, the PbS nanocrystalline thin films were prepared by chemical bath deposition method on the glass and unpolished Si(100) substrates. Triethanolamine was used as additive in the aqueous solution, which resulted in the enhancement of the luminescence of nanocrystalline PbS thin films. The introduction of triethanolamine reduced the grain size and increased the optical band gap of the PbS nanoparticles. The crystalline size of PbS films deposited at two different bath temperatures of 25 °C (PbS-25) and 40 °C (PbS-40) and at different deposition times was estimated to be around 5–50 nm by XRD analyses. The films at 60 °C (PbS-60) were prepared and studied. The structural, morphological and optical properties of the obtained films were investigated. The energy-dispersive X-ray of the typical PbS film was presented, which confirmed the formation of PbS. The mechanism of growth of the PbS crystallites at different bath temperatures was described. The confinement was reflected in absorption and photoluminescence spectra. The variation of the photoluminescence intensity of PbS nanocrystals with triethanolamine molarity, deposition time and bath temperature was investigated. The PbS thin films were found to exhibit PL in both the ultraviolet and visible regions via quantum size effects, surface states and excitation wavelength variation. The luminescence of Si(100) substrate and PbS nanocrystalline films deposited on Si(100) were compared, and the results revealed that the PbS nanocrystals altered and notably enhanced the emission features of the Si(100) substrate. The multi-peak fitting using Gaussian function was employed for the photoluminescence spectrum of PbS on Si(100) substrate.