title: Counter Electrode Impact on Quantum Dot Solar Cell Efficiencies.
abstract: The counter electrode (CE), despite being as relevant as the photoanode in a quantum dot solar cell (QDSC), has hardly received the scientific attention it deserves. In this study, nine CEs (single-walled carbon nanotubes (SWCNTs), tungsten oxide (WO3), poly(3,4-ethylenedioxythiophene) (PEDOT), copper sulfide (Cu2S), candle soot, functionalized multiwalled carbon nanotubes (F-MWCNTs), reduced tungsten oxide (WO3-x), carbon fabric (C-Fabric), and C-Fabric/WO3-x) were prepared by using low-cost components and facile procedures. QDSCs were fabricated with a TiO2/CdS film which served as a common photoanode for all CEs. The power conversion efficiencies (PCEs) were 2.02, 2.1, 2.79, 2.88, 2.95, 3.78, 3.66, 3.96, and 4.6%, respectively, and the incident photon to current conversion efficiency response was also found to complement the PCE response. Among all CEs employed here, C-Fabric/WO3-xoutperforms all the other CEs, for the synergy between C-Fabric and WO3-xcomes to the fore during cell operation. The low sheet resistance of C-Fabric and its high surface area due to the meshlike morphology enables high WO3-xloading during electrodeposition, and the good electrocatalytic activity of WO3-x, the very low overpotential, and its high electrical conductivity that facilitate electron transfer to the electrolyte are responsible for the superior PCE. WO3-based electrodes have not been used until date in QDSCs; the ease of fabrication of WO3films and their good chemical stability and scalability also favor their application to QDSCs. Futuristic possibilities for other novel composite CEs are also discussed. We anticipate this study to be useful for a well-rounded development of high-performance QDSCs.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Hyderabad , Kandi, Sangareddy 502285, Telangana, India.
authors.forename: P Naresh
authors.initials: PN
authors.lastname: Kumar
authors.affiliation: Department of Chemistry, Indian Institute of Technology Hyderabad , Kandi, Sangareddy 502285, Telangana, India.
authors.forename: Ankita
authors.initials: A
authors.lastname: Kolay
authors.affiliation: Department of Chemistry, Indian Institute of Technology Hyderabad , Kandi, Sangareddy 502285, Telangana, India.
authors.forename: S Krishna
authors.initials: SK
authors.lastname: Kumar
authors.forename: Prabir
authors.initials: P
authors.lastname: Patra
authors.forename: Ashish
authors.initials: A
authors.lastname: Aphale
authors.affiliation: CSIR-National Physical Laboratory , Dr. K. S. Krishnan Road, New Delhi 110012, India.
authors.forename: Avanish Kumar
authors.initials: AK
authors.lastname: Srivastava
authors.affiliation: Department of Chemistry, Indian Institute of Technology Hyderabad , Kandi, Sangareddy 502285, Telangana, India.
authors.forename: Melepurath
authors.initials: M
authors.lastname: Deepa
keywords: counter electrode; efficiency; liquid junction; quantum dots; solar cells