Fabrication of praseodymium-doped cadmium selenide thin films for enhanced gas sensing applications

In this work, praseodymium (Pr) was doped into cadmium selenide (CdSe) thin films at concentrations of 0 %, 1 %, 2 %, 3 %, 4 %, and 5 %, and deposited onto glass substrates using the nebulizer spray pyrolysis (NSP) method. The structural, morphological, optical, and photoluminescence (PL) characteristics of the films were investigated. Structural analysis confirmed the crystalline nature and preferred orientation of all the deposited films. Optical studies revealed the interaction of the films with light, with the optical band gap (Eg) decreasing from 2,47 eV for pure CdSe to 2.15 eV for 5 % Pr-doped CdSe. The PL spectra of the as-deposited films showed high intensity in the visible region, with broad UV emission bands centered at 685 nm and 530 nm, respectively. Among the samples, the 3 % Pr-doped CdSe film demonstrated the highest responsivity and repeatability, which is attributed to a higher concentration of selenium vacancies that enhances charge carrier separation. Notably, the 3 % Pr-doped CdSe film exhibited the highest gas response of 259 at 250 ppm. These results suggest that 3 % Pr-doped CdSe is a promising candidate for gas sensing applications due to its superior performance characteristics.