The electron transport layer (ETL) increases the power conversion efficiency (PCE) in organic photovoltaic cells (OPVs) by promoting the formation of ohmic contact between the active layer and the cathode metal.

PSS/MEH-PPV/IF-dione-F/AI (gate)/IF-dione-F/Al (source). The characteristics of the vertical organic light emitting transistors were investigated from the measurements of radiancevoltage characteristics and external quantum efficiency. Furthermore, air stability was studied from the measurements of characteristics, impedance spectroscopy and contact angle.

In this study, we fabricated and studied the device characteristics of vertical organic transistors consisting of nano-patterned gates constructed from the self-assembly of block copolymer. The size of the gate opening made by the new method was 30~40 nm. The device was compared with those which had gate openings of 200 nm. These lager devices were constructed from monodispersed colloidal polystyrene spheres. The device which used block copolymer showed significant improvements in its on-off ratio. We also fabricated transistors with tungsten oxide buffer layer to increase the on current of the device. The devices were analyzed based on their current-voltage charac- teristics, impedance spectroscopy, atomic force microscope (AFM) images and scanning electron microscope (SEM) images.

We have fabricated P3HT and PCBM-based organic photovoltaic cells using DMDCNQI as a guest dopant material and an n-type buffer layer. We have investigated the physical effects of the DMD-CNQI molecule as a guest dopant and an n-type charge transfer buffer layer on the performance of the device by examining measurements of light current-voltage and photoluminescence characteristics. The device using DMDCNQI as a dopant and a buffer layer exhibited a remarkable increase in short-circuit current density (Jsc) due to the ability of an electron acceptor and to the formation of a highly conducting charge transfer complex. In particular, the device consisting of ITO/PEDOT:PSS/P3HT:PCBM:DMDCNQI(1 wt%)/DMDCNQ/Al showed a maximum power conversion efficiency of 3.50%.