Carrier Injection and Transport of Steady-State High Current Density Exceeding 1000 A/cm2in Organic Thin Films*

We demonstrate carrier injection and transport of steady-state high current density into organic thin films. The maximum current density reaches J =1053A/cm 2 , the highest ever reported. We employ a 25 nm-thick Copper phthalocyanine (CuPc) thin film sandwiched between an indium-tin-oxide anode and a magnesium-silver alloy cathode with an active electrode dot-size ( S ) of S =2.0 × 10 -5 cm 2 (radius: r =25 µm). We observed that the maximum current density depends on the organic materials used, and the device size and thickness. Decreasing the organic layer thickness significantly changes the current density-voltage ( J - V ) characteristics, demonstrating that the rate-limiting step of the J - V characteristics changes from the carrier transport process to the carrier injection process. Our achievement of high current density exceeding 1000 A/cm 2 in organic thin films is a first step towards the development of organic laser diodes that need extremely high excitation intensity.