Enhanced organic light emitting diode and solar cell performances using silver nano-clusters

Silver nano-clusters (NCs) were incorporated into organic light emitting diodes (OLED) and solar cells by means of thermal evaporation. Silver NCs enhance the efficiency of both OLEDs and polymer solar cells under tailored device architecture. In tris-(8-hydroxyquinoline) aluminum (Alq₃) based small molecule OLEDs, silver NCs were deposited under the Al cathode. The electron injection from the cathode to organic layer is promoted significantly owing to silver NCs induced lightning rod effect, the Alq₃ OLEDs luminous efficiency is increased up to a factor of 6. In poly(3-hexylthiophene) (P3HT) polymer solar cells, the active layer absorption is enhanced in the presence of silver NCs, which can be ascribed to NCs induced light scattering effect as well as to plasmon enhanced local electric field effect. As a result, photocurrent of the solar cells is increased and the power conversion efficiency (PCE) is improved up to 20%. The comparative study of surface plasmon effects in different organic optoelectronic devices reveals interesting features of the surface plasmon and allows optimization of optoelectronic devices from a novel point of view.