Figure 5.

(a) EL efficiency at an internal electric field (0.3 MV cm⁻¹) of ITO/PEDT:PSS (65 nm) ∕ F 8 BT (x nm) ∕ Ca (5 nm) ∕ Al (400 nm) LEDs with/without the TFB interlayer as a function of F8BT film thickness, (b) Current–voltage–luminance and (c) EL efficiency-voltage characteristics of LEDs (x = 50 nm). Schematic of the device structure and the chemical structures of TFB and F8BT are shown. F8BT is a highly luminescent semiconducting polymer that emits green–yellow light, and has a large ionization potential (5.8 eV) and a large electron affinity (2.95 eV). (Reprinted with permission from [38], ©2005 American Institute of Physics.)