Pt/CuSe composite counter electrode for high efficiency Pb5Sb8S17 quantum dot-sensitized solar cells.

Nipapon Suriyawong^1*, 李明威¹

¹Institute of nanoscience and department of Physics, 國立中興大學, 台中, Taiwan

* Presenter:Nipapon Suriyawong, email:xiaozhen_benny@hotmail.com

Pt is the most commonly used counter electrode for dye-sensitized solar cells. Meanwhile, CuSe has been shown to be an effective CE for semiconductor quantum dot-sensitized solar cells (QDSCs). All QDSCs this day employed only single counter electrode material. In this work, we study the effect of combined two counter electrode materials on the performance of QDSCs. Pt nanoparticles were first grown on FTO glass. Nanosheet structured Cu-Se thin films were subsequently grown on top of the Pt nanoparticles chemical solution deposition. The synthesized CuSe nanosheets, size 150-200 nm, have an energy gap Eg of 1.81 eV. Composite Pt/CuSe CE-based Pb5Sb8S17 QDSCs were fabricated using a polyiodide electrolyte. Three types of counter electrodes (CEs) - Pt, CuSe and Pt/CuSe were tested and compared. The photovoltaic performance depends on the CE and deposition time. The best cell obtained with 3 h Pt/CuSe CE, exhibited a PCE of 3.71% under 1 sun which is 46% and 39% higher than that of the Pt and CuSe CE respectively. At the reduced light intensity of 0.1 sun, the PCE increased to 5.54%. Electrochemical impedance spectroscopy affirms that high PCE value in Pt/CuSe CE is due to the elevated electro-catalytic activity towards polyiodide electrolyte reduction and also the decreased in the charge transfer resistance at the CE-electrolyte interface. This improvement is attributed to the high electrical conductivity and good electrocatalytic ability of the composite Pt-CuSe CE.

Keywords: composite , copper selenide, counter electrode, Charge transfer resistance, nanosheet