| We demonstrate a new class of low reflectivity, high transparency, non-metallic cathodes that may be useful for a wide range of electrically active, transparent organic devices. The metal-free cathode employs an organic thin film capped with a film of low power, radio frequency sputtered ITO. The organic thin film prevents damage to the underlying emissive organic layers during the ITO sputtering process. Due to the low contact reflectivity, a non-antireflection-coated, metal-free transparent organic light emitting device (MF-TOLED) is demonstrated that is >88% transmissive in the visible, emitting nearly identical amounts of light in the forward and back-scattered directions.; We then used these new metal-free cathodes to fabricate a novel transparent, metal-free, full-color stacked organic light emitting device (SOLED). The surface-emitting stack consists of red, blue and green subpixels with total external quantum efficiencies of 2.1%, 1.1%, and 0.75%, respectively. The use of bathocuproine (BCP) as the organic thin film in the compound ITO/organic cathode in the subpixels results in ∼70% transparency across the visible for the entire stack. In addition, an insulating layer in the stack enables all the subpixels to be biased with respect to a common ground reference. This independently tunable, surface emitting, full color device is suitable for integration with the active electronics of existing display schemes.; In order to further optimize the electrical performance of OLEDs employing metal-free cathodes, Li doping in metal-free cathodes was studied. Doped cathodes were incorporated onto conventional bilayer small molecule OLEDs. Device performance comparable to the best undoped OLEDs employing conventional thick metallic cathodes was realized using these new doped metal-free cathodes.; We then studied the effects of Li incorporation in the cathodes of organic light emitting devices. A thermally evaporated surface layer of metallic Li is found to diffuse through and subsequently dope the electron transporting organic semiconducting thin films immediately below the cathode, forming an ohmic contact.; Finally, we examined energy transfer mechanisms to understand and optimize device performance in hybrid inorganic quantum dot-OLED systems for applications to solid-state lighting technologies. OLEDs represent a diffuse source of light and are naturally suited to general-lighting applications. |
