## 1 Introduction  
The usage of solar power is one of the key alternatives to the issue of global warming, rising energy demands, and declining energy sources. It is estimated that the volume of solar energy on the Earth's surface is over 20,000 times that needed at present by humans to create the impression of inexhaustibility. We need transportable and conveniently processed energy for the optimal usage of any energy source. This implies that the incoming solar energy should be effectively stored or transported, which can be achieved through a solar thermal system. Thus, solar energy can contribute to significant savings of common energy resources like coal, oil, and natural gas. Solar thermal systems are non-polluting and do not emit greenhouse gases during their operation. They could also save considerable fossil fuel and electricity consumption, which is currently used for domestic applications [1; 2] since conventional heat transfer fluids have many limitations, such as poor thermal conductivity, high viscosity, uncontrollable pressure drop, and pumping power. Researchers have found a new class of heat transfer fluid (HTF) called 'nanofluids', which is defined as a colloidal suspension of nanosized solid particles incorporated with common base fluids to obtain superior thermophysical properties such as thermal conductivity, viscosity, density, and specific heat capacity. In general, these fluids are mainly utilized for cooling, however, there is not enough research to describe its potential in electronic devices where electrical conductivity is a major concern. Owing to the creation of an electrical double layer, the nanoparticles scattered in the base fluids are charged along the particle surface in nanofluids. When a chargeis applied, these nanoparticles migrate effectively to the oppositely charged electrode leading to high electrical conductivity. [PERSON] et al. [3] reported a comprehensive review of nanofluidselectrical conductivity in recent applications. Therefore, this study concentrated on exploring the electrical and optical potential of nanofluids containing MXene and ionic liquid-based solvent. Compared to optical properties, nanofluids' thermal properties have been investigated for a long time in numerous researches. Recent studies on the optical investigation of nanofluids are summarized as follows: [PERSON] et al. [4] compared the optical property of ZnO nanoparticles dispersed with different base fluids (DMSO, DMF, DI water, and ethanol) at different volume concentrations and laser intensity. The authors observed a unique saturation absorption and self-defocusing behavior for ZnO/DMSO nanofluid, which can be used for non-linear optical devices. Unfortunately, the authors have not discussed the optical properties of the tested nanofluids towards different temperature ranges. [PERSON] et al. [5] used graphene oxide nanoparticles with a base fluid containing a mixture of biphenyl and diphenyl oxide. They reported that graphene oxide addition increased the extinction coefficient in the entire wavelength of the spectrum, proving the presence of heat transfer fluid-absorption band, which is responsible for the heat transfer process enhancement. [PERSON] et al. [6] explored the advantage of Si-MWCNT/EG nanofluids on the performance of a direct absorption solar collector (DASC). In the infrared and visible regions of UV spectroscopy, the authors obtained remarkable solar irradiation absorption. Moreover, 99.9% of solar energy was absorbed in 0.5 wt% of SiC-MWCNT nanofluid, making them a potential candidate as an HTF for DASC. However, they have not considered other important factors, such as pressure drop and pumping power. In an interesting study, [PERSON] et al. [7] distinguished the optical property of SiC/water and CuO/water nanofluid porous metal foam in a DASC. They pointed out that the thermal efficiency of absorption solar collectors depends mainly on the optical properties of absorbers.