NOVELTY - An active layer ink composition comprises p-type material(s), n-type material(s), first solvent(s), and second solvent(s). The first solvent is different from the second solvent. It comprises alkylbenzene(s) or benzocyclohexane. The second solvent comprises carbocyclic compound(s).    USE - The active layer ink composition is used for preparing active layer of photovoltaic device. It is for application to a surface(s) i.e. surface of a component of photovoltaic device (claimed) i.e. organic photovoltaic device, preferably organic solar cell.    ADVANTAGE - The second solvent increases the average surface roughness of active layer to 5-20, preferably 8-10 nm. It can be used at lesser amounts, but improves the efficiency of active layer. The device efficiency is greater than or equal to 5%. The active layer ink composition is free of halogenated compounds. Thus, it is less hazardous. The n-type and p-type materials may be selected to maximize the difference between the lowest unoccupied molecular orbital level of the n-type with the highest occupied molecular orbital level of the p-type, while still maintaining photocarrier generation within the active layer. The improvement in efficiency with the use of the second solvent is greater than or equal to 1, preferably greater than or equal to 50%.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a photovoltaic device comprising an anode, a cathode, and an active layer located between the anode and cathode, where active layer is prepared from the active layer ink composition;    (2) a method comprising combining p-type material(s), n-type material(s), first solvent(s), and second solvent(s) to form active layer ink composition; and applying the active layer ink composition to a surface(s);    (3) a method of forming a photovoltaic device comprising providing an anode; providing a cathode; and forming an active layer between the anode and cathode by applying active layer ink composition to a surface(s) between the anode and cathode; and    (4) a method of improving the efficiency of photovoltaic device comprising adding to an active layer ink composition, an amount of second solvent(s) to increase the average surface roughness of an active layer formed from the active layer ink composition.