A near-infrared (1.5 mu m) to visible light (green) electro-optical upconverter with amplified power gain has been designed and demonstrated. The device was fabricated by direct tandem integration of an organic light emitting diode with an inorganic InGaAs/InP hetero-junction phototransistor. An overall external upconversion power efficiency of 155% was measured at room temperature, demonstrating the utility of hybrid organic/inorganic semiconductor systems.