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 (WO), poly(3,4-ethylenedioxythiophene) (PEDOT), copper sulfide (CuS), candle soot, functionalized multiwalled carbon nanotubes (F-MWCNTs), reduced tungsten oxide (WO), carbon fabric (C-Fabric), and C-Fabric/WO) were prepared by using low-cost components and facile procedures. QDSCs were fabricated with a TiO/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/WO outperforms all the other CEs, for the synergy between C-Fabric and WO comes 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 WO loading during electrodeposition, and the good electrocatalytic activity of WO, the very low overpotential, and its high electrical conductivity that facilitate electron transfer to the electrolyte are responsible for the superior PCE. WO-based electrodes have not been used until date in QDSCs; the ease of fabrication of WO films 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.

Sequential Solution Polymerization of Poly(3,4-ethylenedioxythiophene) Using V2O5 as Oxidant for Flexible Touch Sensors

“…These two peaks resemble the first- and second-order diffraction peaks, suggesting the existence of crystal region. The first peak corresponds to a d-spacing of 3.6 Å, which is close to the typical π-π stacking distance, signifying that some PEDOT chains in SSP PEDOT have a well-ordered π-π stacking (Kumar et al., 2016, Sun et al., 2015b, Chen et al., 2017, Wang et al., 2018b, Rudd et al., 2018). However, the result cannot rule out the possibility that the crystalline PEDOT domains could be embedded in an amorphous PEDOT matrix (Rolland et al., 2018, Gueye et al., 2016).…”

Stability, Scale-up, and Performance of Quantum Dot Solar Cells with Carbonate-Treated Titanium Oxide Films

“…In a previous elaborate study by our group on CEs, we found that carbon (C)-fabric/WO 3−x serves as an excellent CE, for the cell with this CE exhibited the highest PCE of 4.6%, and this was attributed to the least polysulfide reduction potential, a reasonably good electrocatalytic activity, and a low sheet resistance of the C-fabric (9−15 Ω cm −2 ) and its meshlike morphology that maximized WO 3−x loading. 24 Here, QDSCs with the configuration TiO 2 −CBN/CdS/Au@PAA-polysulfide/SiO 2 gel−C-fabric/WO 3−x showed high PCEs, high fill factors (FFs), and reasonably good stabilities as well. The effect of carbonate treatment on stability and performance is explained, and how this treatment is effective in preserving high PCEs to some extent upon scale-up to large area cells with active areas of 1 cm 2 and even 4 cm 2 is also demonstrated.…”

Sequential Solution Polymerization of Poly(3,4-Ethylenedioxythiophene) Using V<Sub>2</Sub>O<Sub>5</Sub> as Oxidant for Flexible Touch Sensors

“…These two peaks resemble the first-and second-order diffraction peaks, suggesting the existence of crystal region. The first peak corresponds to a d-spacing of 3.6 Å , which is close to the typical p-p stacking distance, signifying that some PEDOT chains in SSP PEDOT have a wellordered p-p stacking (Kumar et al, 2016;Sun et al, 2015b;Chen et al, 2017;Wang et al, 2018b;Rudd et al, 2018). However, the result cannot rule out the possibility that the crystalline PEDOT domains could be embedded in an amorphous PEDOT matrix (Rolland et al, 2018;Gueye et al, 2016).…”