NOVELTY - An electrolyte formulation comprises: at least one compound containing cyano-alkoxy-borate anions.    USE - As electrolyte formulation, for forming electrochemical and/or optoelectronic device selected from photovoltaic cell, light emitting device, electrochromic or photo-electrochromic device, electrochemical sensor, biosensor, primary battery, secondary battery, capacitor, supercapacitor (claimed), and electrochemical cells. The batteries are lithium batteries or lithium ion batteries. The capacitor is lithium ion capacitor. The photovoltaic cell is dye sensitized solar cell. The compounds containing cyano-alkoxy-borate anions with organic cations are further useful as solvent or solvent additive for transition-metal- or enzyme-catalyzed reactions, such as hydroformylation reactions, oligomerization reactions, esterifications or isomerizations, and as solvents for carbohydrate containing solids, such as biopolymers and their derivatives or degradation products; as acidic phase-transfer catalyst (containing H+ cation); as extractant to separate off reaction products, and impurities, and as separation media in separation of several components e.g. in distillative separation of components of mixture; as heat-transfer medium, as surface-active substance; as plasticizer in polymer materials; as conductive salt, organic salt, or additive in electrochemical cells and applications e.g. galvanic cells, capacitors or fuel cells; as lubricants; as working fluids for machines such as compressors, pumps or hydraulic devices; and as medium or additive for particle or nanomaterial synthesis.    ADVANTAGE - The electrolyte provides improved electrolyte based on ionic liquids having improved properties such as provides improved dye sensitized solar cell (DSSC) efficiency. The electrolyte formulation having compound containing cyano-alkoxy-borate anions is useful for electrochemical and/or optoelectronic devices, where the formulation shows increased power conversion efficiency in a broad temperature range (-20 to 85 degrees C), particularly under low temperature, for photovoltaic cell, light emitting device, electrochromic or photo-electrochromic device, electrochemical sensor and/or biosensor (preferably DSSC, or quantum dot sensitized solar cell; especially DSSC). The advantage of use of compounds containing cyano-alkoxy-borate anions is their low viscosity; and subsequently smaller Nernst diffusion resistance of oxidant species especially, at lower temperature.    DETAILED DESCRIPTION - An electrolyte formulation comprises: at least one compound containing cyano-alkoxy-borate anions of formula (B(CN)4-x(OR')x)- (I).    x=1 or 2;    R'=straight-chain or branched 1-12C alkyl (optionally partially substituted by halo).    INDEPENDENT CLAIMS are included for the following:    (1) an electrochemical and/or optoelectronic device comprising the electrolyte formulation;    (2) new compound containing cyano-alkoxy-borate anions of formula (Kt1)z+ z(B(CN)4-x(OR')x)- (Ia); and    (3) preparation of the compound containing cyano-alkoxy-borate anions.    Z=1-4;    (Kt1)z+=e.g. H+; inorganic cation e.g. NO+, Li+, Mg2+, Y3+, Yb3+; organic cation selected from complex (ligands containing) metal cations including rare-earths, transitions or noble metals such as rhodium, ruthenium, iridium, palladium, iron; or oxonium cation of formula ((R'a)3O)+ (i), sulfonium cation of formula ((R'b)3S)+ (ii), ammonium cation of formula (N(R'd)4)+ (iii), phosphonium cation of formula (P(R2)4)+ (iv), uronium cation of formula (C(NR3R4)(OR5)(NR6R7))+ (v), thiouronium cation of formula (C(NR3R4)(SR5)(NR6R7))+ (vi), guanidinium cation of formula (C(NR8R9)(NR10R11)(NR12R13))+ (vii), or heterocyclic cation of formula (HetN)z+ (viii) selected from 30 cations as given in the specification e.g. imidazolium cation of formula (viiia), pyrrolidinium cation of formula (viiib), pyridinium cation of formula (viiic), piperazinium cation of formula (viiid), and indolium cation of formula (viiie);    R'a=straight-chain or branched 1-8C alkyl, or phenyl (optionally substituted by R'a, OR'a, N(R'a)2, CN, or halo);    R'b=R'a, or (R'c)2N;    R'c=straight-chain or branched 1-6C alkyl;    R'd, and R2=e.g. OR'e, straight-chain or branched 1-20C alkyl, straight-chain or branched 2-20C alkenyl having at least one double bond (having 1 or 2 of R'd, and R2 optionally partially or fully substituted; and 1 or 2 non-adjacent carbon atoms in R'd, and R2 which are not in the alpha -position optionally replaced by atoms and/or atom groups selected from T'1);    R'e=H, straight-chain or branched 1-18C alkyl (optionally partially fluorinated or perfluorinated), saturated 3-7C cycloalkyl, or optionally substituted phenyl;    T'1=e.g. -O-, -SO2-, -C(O)O-, -N+(R'e)2, -P(O)R'eO-;    R3, R4, R6 and R7=e.g. H, straight-chain or branched 1-20C alkyl, optionally partially or fully unsaturated 3-7C cycloalkyl (having 1 or 2 of R3, R4, R6 and R7 optionally partially or fully substituted; and 1 or 2 non-adjacent carbon atoms in R3, R4, R6 and R7 which are not in the alpha -position optionally replaced by atoms and/or atom groups selected from T'1);    R5=e.g. straight-chain or branched 1-20C alkyl, straight-chain or branched 2-20C alkenyl having at least one double bond, straight-chain or branched 2-20C alkynyl having at least one triple bond (having 1 or 2 R5 optionally partially or fully substituted; and 1 or 2 non-adjacent carbon atoms in R5 which are not in the alpha -position optionally replaced by atoms and/or atom groups selected from T'1);    R8 to R13=e.g. OR'e, straight-chain or branched 1-20C alkyl, straight-chain or branched 2-20C alkenyl having at least one double bond (having 1 or 2 of R8 to R13 optionally partially or fully substituted; and 1 or 2 non-adjacent carbon atoms in R8 to R13 which are not in the alpha -position optionally replaced by atoms and/or atom groups selected from T'1);    R'1, R'2, R'3, and R'4=T1, or T2 (having 1-3 substituents from R'1 to R'4 optionally partially or fully substituted; and 1 or 2 non-adjacent carbon atoms in the R'1 to R'4 which are not bonded to the heteroatom optionally replaced by atoms and/or atom groups selected from T'1);or    R'1, R'2, R'3 and/or R'4 taken together=ring system;    T1=e.g. H, N(R'e)2, P(O)(R'e)2;    T2=e.g. H, straight-chain or branched 1-20C alkyl (optionally fluorinated or perfluorinated), heteroaryl-1-6C-alkyl.    Provided that:    (1) R'1, R'3, and R'4 are selected form T1, or T2;    (2) R'2 is selected from T1; and    (3) R'1 and R'4 cannot simultaneously be fully substituted by halo.    Full Definitions are given in the DEFINITIONS (Full Definitions) section.