Evaluation of carrier transport and recombinations in cadmium selenide quantum-dot-sensitized solar cells

• DOI: 10.1016/j.solmat.2012.02.014
• Publication Date: 2012-03-06T03:57:36Z
• Authors: Saim Emin; Masatoshi Yanagida; Wenqin Peng; Liyuan Han
• Keywords: 02 engineering and technology; 0210 nano-technology; 7. Clean energy

Abstract In this paper, we present a study on cadmium selenide (CdSe) quantum-dot-sensitized solar cells (QDSSCs) in terms of the evaluation of carrier transport and recombinations using intensity-modulated photovoltage spectroscopy (IMVS) and intensity-modulated photocurrent spectroscopy (IMPS). Using the obtained data through this evaluation, we calculated the electron transport time ( τ sc ), electron recombination lifetimes ( τ oc ), effective diffusion constants ( D eff ), and diffusion lengths ( L n ). The QDSSC used in this study show improved fill factors ( FF ) of ∼60% with a polysulfide (S 2− /S x 2− ) redox mediator and Pt counter electrode. This result is ascribed to the low series resistances ( R s ) of QDSSC that are accessed by electrochemical impedance spectroscopy. In addition, the present study provides information on the sensitization mode of CdSe QDs on TiO 2 electrodes, achieved by scanning transmission electron microscopy (STEM) combined with EDS imaging.