NOVELTY - The solar cell device comprises an anode, an organic photovoltaic device active layer disposed on the anode, an interfacial modification layer disposed on the active layer, a cathode disposed on the interfacial modification layer, and a transparent substrate. The active layer comprises a p-type material and an n-type material. The interfacial modification layer comprises a dopant and an organic semiconductor. The anode comprises a transparent conductor. A hole transport layer is present between the anode and the active layer. The interfacial modification layer is 1-30 nm thick.    USE - The solar cell device is useful in a module that generates electrical power and currents.    ADVANTAGE - The solar cell device has excellent efficiency including power conversion efficiency and stability and improved lifetime under harsh humidity, temperature and time conditions.    DETAILED DESCRIPTION - The solar cell device comprises an anode, an organic photovoltaic device active layer disposed on the anode, an interfacial modification layer disposed on the active layer, a cathode disposed on the interfacial modification layer, and a transparent substrate. The active layer comprises a p-type material and an n-type material. The interfacial modification layer comprises a dopant and an organic semiconductor. The anode comprises a transparent conductor. A hole transport layer is present between the anode and the active layer. The interfacial modification layer is 1-30 nm thick. The active layer is 150-250 nm thick. The interfacial modification layer organic semiconductor has a HOMO value lower in energy than the HOMO value of the active layer conjugated polymer. The p-type material and n-type material of the active layer are present in a ratio of 1 n-type to 1-2 p-type materials. The dopant comprises alkali metals, alkali earth metals, transition metals, rare earth metals and metal oxides, and an organic material.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a solar cell device.    Substrate (102)    Anode (104)    Hole transport layer (106)    Active layer (108)    Optical spacer layer (110)    Cathode. (112)