Improving the stability of CdS quantum dot sensitized solar cell using highly efficient and porous CuS counter electrode

Abstract

Thin films from copper sulfide (CuxS) are the most commonly used electrocatalyst counter electrodes (CEs) for high-efficiency quantum dot sensitized solar cells (QDSSCs) because of its superior electrocatalytic activity in the presence of polysulfide electrolytes. In addition to the stability issues, the CuxS CEs are usually prepared by complicated, costly, time consuming, and less productive methods, which are inadequate for practical applications of QDSSCs. In this work, we present a simple approach for fabricating an efficient and stable CE for QDSSCs using pure covellite phase CuS nanoparticles (NPs) pre-prepared via a cheap, fast, and scalable chemical method. The catalyst ink was obtained by mixing the as-prepared CuS NPs with polyvinylidene fluoride, as a polymeric binder, which was then directly applied to a conductive fluorine-doped tin oxide substrate without any further high temperature post treatment. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization measurements were used to investigate the electrocatalytic activity of the CuS NPs CE. The power conversion efficiency of 2.6% was achieved from CdS QDSSC assembled with CuS NPs CE, which was higher than 1.57% for conventional Cu2S/brass and 1.33% for Pt CEs under one-sun illumination. The CdS QDSSC with CuS NPs CE was also able to supply a constant photocurrent value without any obvious decrease under light soaking test, in contrast to the devices with Cu2S/brass and Pt CEs, which showed inferior stability. This remarkable photovoltaic performance was attributed to the nanoporous morphology and the excellent electrocatalytic activity of CuS NPs CE.

Impedance Spectroscopy: A Versatile Technique to Understand Solution‐Processed Optoelectronic Devices

“…IS is in fact a comparative technique that has been used for optimization of solar cells in past years . It provides primary electronic parameters in the working conditions of the solar cell.…”

In Situ Microwave‐Assisted Fabrication of Hierarchically Arranged Metal Sulfide Counter Electrodes to Boost Stability and Efficiency of Quantum Dot‐Sensitized Solar Cells

“…Additionally, low cost and convenient fabrication of QDSSCs photovoltaic devices are of paramount importance in overcoming the hurdle of commercially lucrative cells' production. Over the years, several semiconductor QDs, such as CdS, CdSe, PbS, and CuInS 2 , have been introduced, and significant progress in achieving higher power conversion efficiency (PCE) has been made. However, the champion PCE of 12.75% is still far behind the maximum thermodynamic conversion efficiency of 44% …”

Photoactive Core–Shell Nanorods as Bifunctional Electrodes for Boosting the Performance of Quantum Dot Sensitized Solar Cells and Photoelectrochemical Cells

“…Among the cost-effective strategies to convert and store solar energy in the form of chemical fuels, colloidal QD based photovoltaic (PV) devices, with rapid progress in PCE exceeding 12%, and PEC cells have attracted considerable attention. , The credence in their ability to reach and even cross the Shockley–Queisser limit in QDSSCs, is due to the tunable optoelectronic properties of QDs such as high absorption coefficient and multiple exciton generation. − In order to boost the PCE of QDSSCs, although the photoanodes have received major attention, − effective design of the electrolyte, , and CE also play integral roles. − Different materials have been employed as CE and among them the metal chalcogenides, such as Cu x S, ,− , PbS, , CoS, , and Cu–Zn–Sn-S, have been manifested as premier electrocatalysts to reduce the oxidized electrolyte S n 2– to nS 2– . Despite having low charge transfer resistance ( R CT ), the metal chalcogenides suffer from high sheet resistance, for which the graphene based composites have become viable alternatives. ,− …”