Electrochemical behavior of NH4VO3 in glyceline DES studied by cyclic voltammetry method

In the present work, the redox behavior of vanadate ion in deep eutectic solvent (DES) was studied via cyclic voltammetry (CV) method where glyceline DES and NH4VO3 were used as electrolyte and the source of + 5 vanadium ions respectively. The CV showed a quasi-reversible redox couple pattern of + 5 to + 4 vanadium ions in glyceline DES. Analysis by UV-Vis revealed the presence of + 3 vanadium ions at λmax 545 nm. The glyceline DES does not only act as a solvent but also as a reducing agent by chemically reducing + 4 vanadium ions to the most stable oxidation state of + 3. Temperature dependence study of vanadate ion in glyceline DES showed that the peak current increased with temperature which enhances the reaction kinetics. In addition, the conductivity of NH4VO3 in glyceline DES improved remarkably with temperature, whereas its viscosity declined. Moreover, the Rs and Rct values decreased with increasing temperature. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature

Raytracing Modelling of Infrared Light Management Using Molybdenum Disulfide (MoS₂) as a Back-Reflector Layer in a Silicon Heterojunction Solar Cell (SHJ)

The silicon heterojunction solar cell (SHJ) is considered the dominant state-of-the-art silicon solar cell technology due to its excellent passivation quality and high efficiency. However, SHJ’s light management performance is limited by its narrow optical absorption in long-wave near-infrared (NIR) due to the front, and back tin-doped indium oxide (ITO) layer’s free carrier absorption and reflection losses. Despite the light-trapping efficiency (LTE) schemes adopted by SHJ in terms of back surface texturing, the previous investigations highlighted the ITO layer as a reason for an essential long-wavelength light loss mechanism in SHJ solar cells. In this study, we propose the use of Molybdenum disulfide (MoS2) as a way of improving back-reflection in SHJ. The text presents simulations of the optical response in the backside of the SHJ applying the Monte-Carlo raytracing method with a web-based Sunsolve high-precision raytracing tool. The solar cells’ electrical parameters were also resolved using the standard electrical equivalent circuit model provided by Sunsolve. The proposed structure geometry slightly improved the SHJ cell optical current density by ~0.37% (rel.), and hence efficiency (η) by about 0.4% (rel.). The SHJ cell efficiency improved by 21.68% after applying thinner back ITO of about 30 nm overlayed on ~1 nm MoS2. The efficiency improvement following the application of MoS2 is tentatively attributed to the increased NIR absorption in the silicon bulk due to the light constructive interface with the backside components, namely silver (Ag) and ITO. Study outcomes showed that improved SHJ efficiency could be further optimized by addressing front cell components, mainly front ITO and MoS2 contact engineering