Preparation of NiCo2S4 Thin Films As Counter Electrodes for Dye-Sensitized Solar Cells Using Dip-Coating Method

Abstract

Dye-sensitized solar cells (DSCs) have attracted intensive attention due to its high efficiency, low cost, and easy fabrication process. The main components of a typical DSC include a photo anode, an I−/I3 − redox electrolyte and a Pt counter electrode (CE). To speed up the commercialization of DSCs, the manufacturing cost of DSCs should be further significantly reduced. Both of exploring alternative CE materials to noble Pt and developing facile and low-cost fabrication process of CEs are crucial for achieving this purpose. In this study, NiCo2S4 (NCS) counter electrodes (CEs) were successfully fabricated via a facile dip-coating method for the first time. Prior to the CE preparation, the NCS particles were synthesized via a hydrothermal method. Afterward, the as-synthesized NCS were ball milled and then dispersed in de-ionized water or ethanol solutions. The bare fluorine-doped tin oxide (FTO) glass substrates were dipped in the surface-conditioner solution for 1 min and subsequently dipped in the as-prepared NSC suspension solution for different times. The Inductively Coupled Plasma Mass Spectrometry (ICP-MS) results showed the mass loadings for both kinds of NCS CEs first increased with immersion time, and then retain almost the same while the immersion time was over than 10 min The NCS CEs prepared by dipping in de-ionized water solutions for 10 min is designated as NCS CE. According to the electrochemical and photovoltaic measurements, NCS CE demonstrated superior electrocatalytic activity. Moreover, NCS showed the low charge-transfer resistance of 1.56 Ω. As a result, the photovoltaic conversion efficiency of the DSC based on the NCS CE was up to 7.36%, significantly higher than the Pt CE (7.29%).