Deep Eutectic Solvents in Solar Energy Technologies.

Chiara Liliana Boldrini,Alessandro Abbotto,Andrea Francesca Quivelli,Vito Capriati,Norberto Manfredi

doi:10.3390/molecules27030709

Abstract

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to properly respond to most important societal needs, is still relatively scarce. This represents a strong limitation since many solar devices make use of polluting or toxic components, thus seriously hampering their eco-friendly nature. Herein, we review the literature, mainly published in the last few years, on the use of DESs in representative solar technologies, from solar plants to last generation photovoltaics, featuring not only their passive role as green solvents, but also their active behavior arising from their peculiar chemical nature. This collection highlights the increasing and valuable role played by DESs in solar technologies, in the fulfillment of green chemistry requirements and for performance enhancement, in particular in terms of long-term temporal stability.

Highlights

The increasing awareness of global climate change, due to continuous CO2 emissions coming from non-renewable fuels combustion, makes the search for novel and different eco-friendly approaches for energy production impelling
A steam generation system using methyltriphenylphosphonium bromide (MTPB)/ethylene glycol (EG) Deep Eutectic Solvents (DESs) as a pseudo-component was simulated, resulting in a steam generation rate increase with both the temperature and the flow rate of DES, implying that the DES can be used for enhancing the heat transfer coefficient in concentrated solar power (CSP) plants
This review showcases that DESs have proven to be highly attractive components for solar devices, both in CSP plants and Dye-Sensitized Solar Cells (DSSCs)

Summary

Introduction

The increasing awareness of global climate change, due to continuous CO2 emissions coming from non-renewable fuels combustion, makes the search for novel and different eco-friendly approaches for energy production impelling. In 2018, they started from the study of a DL-menthol/oleic acid 1:1 DES and, in order to improve the performance, added different concentrations of nano-Al2O3 (70-nm diameter) to obtain 4 different nanoparticle-dispersed DESs (NDDESs) (0.001, 0.005, 0.0075, 0.01 volume fractions) [89] These NDDESs belong to the category of nanofluids, that in the past decade have gained attention for their thermal property enhancement with respect to base fluids. A steam generation system using MTPB/EG DES as a pseudo-component was simulated, resulting in a steam generation rate increase with both the temperature and the flow rate of DES (the best value was 1.7 kg/h of steam produced at 180 ◦C with a corresponding DES flow rate of 1 m3/h), implying that the DES can be used for enhancing the heat transfer coefficient in CSP plants In their latest publication, Dehury completed the study of the previously described DL-menthol/oleyl alcohol 1:1 DES (DL-M/OlOH) by adding 0.02%, 0.05% and 0.1% w/w hexagonal boron nitride (h-BN) nanoparticles (80-nm diameter) and compared it with a novel diphenyl ether + DL-menthol 1:1.2 DES (DPE/DL-M), pure or with h-BN nanoparticles [92]. DSSCs based on KI/EG 1:5 + 0.5% mol I2 showed a marked long-term temporal stability, with still residual 50% efficiency after one month and 40% after seven months, in particular, when compared to reference VOC-cells, whose efficiency dropped to zero after one month because of solvent evaporation

DSSCs Using DES as a Co-Solvent in Combination with VOCs or ILs

Findings

Conclusions