Efficiency improvement in InGaN-based solar cells by indium tin oxide nano dots covered with ITO films.

InGaN based MQW solar cells have been fabricated with 4 different transparent top electrode structures: (1)- ITO 200 nm, (2)-ITO nano dots only, (3)-ITO nano dots on ITO 50 nm and (4)-ITO nano dots on ITO 100 nm. The solar cell with the ITO 50 nm on ITO nano dots under AM 1.5 conditions showed the best results: 2.3 V for V(oc), 0.69 mA/cm(2) for J(sc), 41.8% for peak EQE, and 0.91% for conversion efficiency. Efficiency improvement was possible due to the decreased reflectance achieved by the ITO nano dots covered with an ITO film with optimized thickness.