Improved solar cell performance of chemosynthesized cadmium selenide pebbles

• CdSe thin films have been synthesized by a versatile chemical bath deposition method.
• Effect of air annealing on the as-deposited CdSe thin films with respect to photoelectrochemical measurement is studied.
• FESEM images showed the formation of CdSe pebbles
• The sample annealed at 300 °C produced the maximum current density of 3.90 mA/cm2 with the highest power conversion efficiency 2.08%.

The cadmium selenide pebble-like microstructures have been synthesized by a simple and cost-effective one-step, one-pot chemical bath deposition method onto the soda-lime glass substrates. In order to study the annealing effect on CdSe thin films, as-deposited films were annealed at temperatures 100, 200, 300 and 400 °C respectively for 1 h in ambient air. These films were characterized for their optical, structural, compositional, morphological properties using UV–vis spectrophotometer, Photoluminescence, X-ray diffraction, X-ray photoelectron spectroscopy and field emission scanning electron microscopy techniques. The optical band gap energy was found to decrease from 1.97 to 1.71 eV with increase in annealing temperature exhibiting a red shift. XRD patterns show the formation of amorphous CdSe for as-deposited thin films. Annealing the samples leads to the transition of crystal structure from amorphous to cubic and cubic to hexagonal. The chemical composition and valence states of the constituent elements were analyzed by XPS. FESEM images showed the formation of CdSe pebbles. The maximum current density of 3.90 mA/cm2 for the sample annealed at 300 °C was observed with the highest power conversion efficiency 2.08%.