Volume 8, Issue 3, March 2015
Index of content:
- ORGANIC ELECTRONICS AND PHOTONICS
Suppression of roll-off characteristics of organic light-emitting diodes by narrowing current injection/transport area to 50 nm106(2015); http://dx.doi.org/10.1063/1.4913461View Description Hide Description
Using e-beam nanolithography, the current injection/transport area in organic light-emitting diodes (OLEDs) was confined into a narrow linear structure with a minimum width of 50 nm. This caused suppression of Joule heating and partial separation of polarons and excitons, so the charge density where the electroluminescent efficiency decays to the half of the initial value (J0 ) was significantly improved. A device with a narrow current injection width of 50 nm exhibited a J0 that was almost two orders of magnitude higher compared with that of the unpatterned OLED.
Inkjet printed silver nanowire network as top electrode for semi-transparent organic photovoltaic devices106(2015); http://dx.doi.org/10.1063/1.4913697View Description Hide Description
A method for direct inkjet printing of silver nanowire (Ag NW) to form transparent conductive network as the top electrode for inverted semi-transparent organic photovoltaic devices (OPV) was developed. The highest power conversion efficiency of the poly(3-hexylthiophene):phenyl-C61–butyric acid methyl ester (P3HT:PC61BM) based OPV was achieved to be 2.71% when the top electrode was formed by 7 times of printing. In general, devices with printed Ag NW top electrode had similar open-circuit voltage (V OC, around 0.60 V) but lower fill factor (FF, 0.33–0.54) than that of device with thermally deposited Ag opaque electrode (reference device). Both FF and short-circuit current density (J SC), however, were found to be increasing with the increase of printing times (3, 5, and 7), which could be partially attributed to the improved conductivity of Ag NW network electrodes. The solvent effect on device performances was studied carefully by comparing the current density-voltage (J-V) curves of different devices. The results revealed that solvent treatment on the anode buffer layer during printing led to a decrease of charge injection selectivity and an increase of charge recombination at the anode interface, which was considered to be the reason for the degrading of device performance.