A selenium-based “alkahest”: reactive dissolutions of metals and metal compounds with n-alkylammonium polyselenide solutions

Abstract

The solution-processing of metal chalcogenides offers a promising route to improve the manufacturing of semiconductor devices. The amine-thiol solvent system has been deemed an “alkahest” for its ability to dissolve...

Solution processed metal chalcogenide semiconductors for inorganic thin film photovoltaics

“…Turnley et al further tuned the ink chemistry, eliminating the thiol as a potential sulfur and carbon source to confirm this result. 35,79 In Deshmukh et al and Turnley et al , films were able to fully coarsen at thicknesses greater than 2 μm (Fig. 7), something not previously shown in solution processed Cu(In,Ga)(S,Se) 2 solar cells but standard in vacuum-deposited Cu(In,Ga)(S,Se) 2 PV.…”

“…141,142 Recently, by using a new alkahest dissolution of Ag, Zn, and Sn, Turnley et al were able to solution deposit pure Ag 2 ZnSnSe 4 thin films by dropcasting. 35 These are promising results and should prompt further investigation in designing a better absorber layer and device architecture for Ag 2 ZnSnSe 4 solar cells.…”

“…34 Recently, Turnley et al introduced a sulfur-free, selenium-based alkahest using n -alkylammonium polyselenide solutions and reported CuInSe 2 and Cu(In,Ga)Se 2 absorber films without any fine grain layers. 35 Preliminary CuInSe 2 devices with minimal optimization showed efficiencies up to 7.25% and the potential for improvements is great due to the absence of impurities.…”

“…Another method to remove unreacted thiols and disulfides from the dissolved precursor solutions has been used recently by the Agrawal group. 35,79 In this precipitation–redissolution method, the dissolved precursor is precipitated by adding an antisolvent mixture, centrifuged, decantated, and redissolved in a suitable solvent (Fig. 13).…”

“…As an offshoot of the amine–thiol dissolution chemistry research, the Agrawal group recently presented n -alkylammonium polyselenide ((RNH 3 ) 2 Se x ) solutions as a versatile, selenium-based solvent system for the synthesis of an array of phase pure metal selenide semiconductors. 35 This finding was the result of two important observations: first, that Te could be made soluble in butylamine–ethanethiol solution as Se x Te y 2− complexes when Te is otherwise insoluble in monoamine–monothiol mixtures, 190 and second, through the method of precipitation–redissolution shown in Fig. 13, sulfur-free alkylammonium polyselenides (AAPSe) could be easily synthesized, isolated, and redissolved in an array of polar organic solvents including amines, dimethyl sulfoxide, or dimethylformamide.…”