Quantum dot sensitized solar cells: Effect of nanocrystal size on the efficiency
Bandgap of the CdSe nanocrystals was tailored using low temperature synthesis and these nanocyrstals were used to fabricate ZnO based Quantum Dot Sensitized SolarCell (QDSSC).CdSe nanocrystal size varied from0.85 to 2.25 nmwith increase in synthesis temperature from225 to 255oC. Bandgap of CdSe nanocrystals decreased from 3.50 to 1.97 eV with increase in size from 0.85 to 2.25 nm, resulting in the absorbance of a broader spectrum of visible light in the range 350 to 700 nm. QDSSCs were fabricated by using individual nanocrystals of different size and a blend of all the nanocrystals. As the size of the nanocrystal increased from 0.85 to 2.25 nm, efficiency of QDSSCwas found to decrease from2.06 to 0.25%. The efficiency of colloidal QDSSC cell was obtained to be 3.6%atAM1.5.