The present invention provides a nonaqueous electrolytic solution that provides an electric double layer capacitor having excellent durability. The nonaqueous electrolytic solution of the present invention is a nonaqueous electrolytic solution for electric double layer capacitors prepared by dissolving a quaternary ammonium salt as an electrolyte in a nonaqueous solvent, and the nonaqueous electrolytic solution has an alkali metal cation concentration of 0.1 to 30 ppm.

The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I]; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X]. The invention also relates to a process for producing a semiconductor device comprising said semiconducting material. Also described is a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I] selected from Cu.sup.+, Ag.sup.+ and Au.sup.+; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X].

The present invention relates to a semiconductor device comprising a semiconducting material, wherein the semiconducting material comprises a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I]; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X]. The invention also relates to a process for producing a semiconductor device comprising said semiconducting material. Also described is a compound comprising: (i) one or more first monocations [A]; (ii) one or more second monocations [B.sup.I] selected from Cu.sup.+, Ag.sup.+ and Au.sup.+; (iii) one or more trications [B.sup.III]; and (iv) one or more halide anions [X].

The present disclosure is directed to methods of making Pb-free perovskites for short-wave IR (SWIR) devices and to various Pb-free perovskite materials disclosed herein. The perovskites disclosed herein have improved chemical stability and long-term stability, while the production methods disclosed herein have improved safety and lower cost.