Chemometric optimization of the continuous flow synthesis parameters of PbS thin films: Design of experiments (DOE) based mathematical modelling for energy band gap prediction of PbS coating

In this study, important process parameters in the synthesis of PbS films using a continuous flow reactor were optimized with a design of experiments approach. Flow rate, circulation time and temperature were selected as process parameters in coating with the flow-through chemical deposition method. A mathematical model was developed to predict the energy band gap of PbS chalcogenides deposited using a continuous flow reactor. According to the central composite design results for the chalcogenides, optimum process conditions were found to be flow rate: 146.9 mL/min, circulation time: 6.3 h and temperature: 30.3 °C. ANOVA results showed that the flow rate and reaction temperature parameters are important for the prediction model. In other words, it can be said that these parameters play an important role in controlling the Eg value of PbS. On the other hand, the average surface roughness (Ra: 8.78 nm) and RMS roughness (Rq: 11.34 nm) values of the PbS film synthesized under optimized conditions supported the smooth surface formation phenomenon. The energy band gap of the film-coated under optimal experimental conditions was measured as 2.18 eV and was estimated as 2.15 eV by the developed model. The developed model could predicted the Eg of PbS film with a relative error of 1.38 %. The closeness of the measured and predicted Eg values revealed the reliability of the developed mathematical model.