Quantum dots sensitized solar cell: Effect of CdSe nanoparticles purification procedure of QD sensitized photoanodes

Abstract

In this research the effect of purification of CdSe nanoparticles for application in quantum dots sensitized solar cells (QDSSC) photoanodes are studied. The CdSe nanoparticles are attached to the titanium dioxide surface using a linker based approached (CdSe nanoparticles disperse in toluene) and direct mode attachment (CdSe re-disperse in dichloromethane (DCM)). Colloidal CdSe nanoparticles with estimated size of 3.0 nm were synthesized by hot injection method in trioctylphosphine oxide (TOPO) as stabilizing solvent. Prior to the sensitization, the CdSe nanoparticles were purified using a common purification step involving the alternate cycles of precipitation / redispersion in non-polar solvent and polar solvent. With increasing the number of purification, the concentrations of CdSe nanoparticles attached to the titanium dioxide were also increased; from 2.47 × 1015 dots/cc for 3x wash CdSe nanoparticles to 3.70 × 1015 dots/cc for 4x wash CdSe nanoparticles. Polysulfide electrolyte and Cu2S counterelectrodes were used to assemble a complete QDSSC. The highest efficiency of 0.05% was obtained from 4x wash CdSe nanoparticles; Voc = 0.2V, Jsc = 0.34 mA/cm2 and FF = 0.07).