Copper/cuprous sulfide electrode: preparation and performance.

Cuprous sulfide (CuS) is a direct band-gap p-type semiconductor with excellent ionic/electronic hybrid conductivity. Although Cu/CuS/sulfide or polysulfide system is adopted as counter electrode of quantum-dots-sensitized solar cells (QDSSC), the electrode process is seldom reported. Here, the electrochemical growth of CuS film on a copper (Cu) surface, the redox behaviors of sulfide and polysulfide, and the all-in-solid charge-transfer properties of CuS film are investigated. It is clarified that the copper electrode simultaneously undergoes an activated process, a membrane growth process, and a redox phase transformation process. The solid charge-transfer capability of CuS is quantified with a high exchange-current density of 2.27 A/cm, which elucidates that the Cu/CuS electrode is a qualified material for counter electrodes of QDSSC. These results aid understanding of the physicochemical mechanism of QDSSC with a polysulfide electrolyte and Cu/CuS counter electrode. [ABSTRACT FROM AUTHOR]