Effect of post annealing on the performance of CdSe/P3HT bulk hetero-junction solar cells

Thermal annealing effect on the structural and optical properties of synthesized CdSe nanoparticles has been elucidated and applied on the performance improvement of bulk hetero-junction solar cell. Improvement in crystallinity and cell stabilization of as-synthesized CdSe nanoparticles could be achieved by controlling the annealing parameters. Synthesized and annealed CdSe nanoparticles were characterized by TEM, XRD, XPS, Raman and PL measurements. XRD analysis exhibited annealing-induced phase transition in the nanocrystalline CdSe from cubic Zinc Blende to hexagonal Wurtzite structure. After annealing, the intensity of PL emission peak was substantially increased, and the solar cell with optimized active layer showed enhancement in power conversion efficiency. Post-annealing process parameters for solar cell fabrication were developed based on the studies of thermal annealing effect on CdSe nanoparticles.