The Study on the Quantum Dot Sensitized Solar Cells

Abstract

The Quantum Dot Sensitized Solar Cells (QDSSCs) using Pt as its counter electrode and poly-sulfide redox shuttle have problems on the low QD’s regeneration speed and high over poten-tial. Sulfur compounds induce a poisoning effect because it was chemisorbed onto the Pt sur-face. It leads to poor charge transfer rate (Sn2-+e-→nS2) at the counter electrode and high over potential for the reduction reaction. The Cu2S was proposed as an ideal counter electrode ma-terials for higher performance QDSSCs due to their higher electrical catalytic activity and stabil-ity. In this study, Cu2S nanocrystals (NCs) are proposed as counter electrode. At the result of, the efficiency of QDSSCs using Cu2S NCs as counter electrode is 0.2% higher than that of using the Pt counter electrode. In addition, The rate of reduction of the Cu2S NCs capped with or-ganic ligands replaced with Na2S (Inorganic) ligands lead to significantly increase. It is demon-strated that the rate of reduction process with Na2S_capped Cu2S NCs counter electrode was more 3 times higher than that of organic_ capped Cu2S NCs counter electrode. Electrochemical impedance spectra (EIS) also confirmed much less resistance by using Na2S capped counter electrode. Finally, we also studied on the effects of nanomaterials and surface modification on the operation of QDSSCs using photoanode materials like CdSe which synthesized by SILAR and hot-temperature injection method. ⓒ 2014 DGIST