Insights into the Properties of Deep Eutectic Solvent Based on Reline for Ga-Controllable CIGS Solar Cell in One-Step Electrodeposition

Abstract

A deep eutectic solvent (DES) called Reline has attracted great interests in photovoltaic application. Many efforts have been made to get high efficiency solar cells by electrodeposition in such a low-cost and green electrolyte. In this work, the micro-structure and electrochemical properties of Reline are investigated. The metal complex system of Reline and metal salts is deduced by FTIR and UV-Vis absorption spectroscopy analyses. The theoretical diffusion coefficients of Cu, In and Ga at 65 • C are calculated by Cyclic voltammetry analysis to perform a controllable Ga/(In+Ga) ratio over a large range (0 ∼ 0.53) by different pulse potentiostatic methods. Based on these achievements and optimizations, the best CIGS solar cell device with a promising efficiency of 10.1% is achieved. Solar energy has received increasing interests as an alternative to other sources of energy such as fossil fuels and nuclear energy. [1][2][3][4][5][6] One of the most promising solar cells is based on the polycrystalline Cu(In,Ga)Se 2 (CIGS) fabricated by using vacuum based process whose conversion efficiency is up to 21.7%. 7 Although vacuum techniques seem to be an excellent method for fabricating high efficiency CIGS solar cells, it is challenging to scale up the process for commercial production. While sputtering and evaporation technique could be used for large-area deposition, however, the production process is limited by expensive vacuum equipment as well as large energy consumption. [8][9][10][11] For low-cost fabrication of semiconductor thin films, electrodeposition has been proved to be a viable approach for large scale manufacturing of CIGS.10-13 However, most of the works are carried out in aqueous solvents, in which hydrogen evolution reaction (HER) leads to low plating efficiencies and pinholes in the plating layer.14,15 To avoid the occurrence of HER, researchers in recent years have turned to deep eutectic solvents (DES) as an electrolyte for electrochemical reactions due to their wide electrochemical window, high ionic conductivity, high solvation capacity, negligible vapor pressure and excellent stability. [16][17][18][19][20] Besides, DES, as a subclass of ionic liquids (ILs), is a green electrolyte for application in electroplating. [14][15][16][21][22][23] Reline, as one application of DES, is formed by choline chloride and urea at the ratio of 1:2. Harati et al. fabricated successfully stoichiometric CIGS thin film by the one-pot electrodeposition in Reline as electrolyte.21 Malaquias et al. used Reline to deposit In-Ga on Cu and Mo electrodes and finally obtained solar cell with a 7.9% efficiency. 15 Chen at al reported a 3.87% CZTS solar cell efficiency by co-electrodepositing Cu-Zn-Sn precursor thin films in Reline. 24 Although these studies show the viability of Reline as a green electrolyte, its micro-structure and electrochemical properties are rarely reported and the formed metal complexes in Reline are also needed further investigation. Meanwhile DES is cheap and easy to synthesize and has wide applica...

Deep Eutectic Solvents in Solar Energy Technologies

“…Focusing on solar technologies, in the last decade, DESs have been successfully exploited for the synthesis of active materials in thin film inorganic solar cells, such as active layers of CGS (CuGaSe 2 ) [ 65 , 66 ], CIS (CuInSe 2 ) [ 67 ], CIGS (Cu(In,Ga)Se 2 ) [ 68 , 69 , 70 , 71 ], and CZTS (Cu 2 ZnSnS 4 ) [ 72 ]. A perusal of the recent literature has shown that DESs have also been successfully employed in the synthesis of active materials for water splitting, in particular to be applied in photocatalytic [ 73 ] or photoelectrochemical [ 74 , 75 , 76 , 77 , 78 , 79 , 80 , 81 ] setup, or both [ 82 , 83 ].…”

Nontoxic photoluminescent tin oxide nanoparticles for cell imaging: deep eutectic solvent mediated synthesis, tuning and mechanism

“…56 And in the present study this is inferred due to the following two reasons. Firstly, the bands 3259cm -1 , 1681cm -1 and 1606cm -1 observed in the present sample are characteristically found in urea-water mixtures 56,57 and indicate the presence of water molecules near urea.…”

Dynamics of Glyceline and Interactions of Constituents: A Multitechnique NMR Study

“…The two solvent types have similar properties: low volatility, low flammability, and wide electrochemical (possibly) and thermal stability windows. − However, unlike typical ionic liquids, DESs can be inexpensive, readily synthesized, and can often be prepared from biodegradable, and nontoxic constituents. , Furthermore, the very generality of the DES concept implies an enormous number of possible HBD/HBA combinations. On the positive side, this has led to their applicability in a variety of processes, ,− as well as in electrochemical applications. − However, given the many possible combinations of H-bond donors and acceptors that can form DESs, the possibility of tailoring DESs for specific applications requires more detailed studies of the effects of HBD/HBA types on the aspects controlling transport properties, such as the underlying dynamic structures formed in the liquids, a daunting prospect.…”