Highly photosensitive organic phototransistors (OPTs) with an organic thin film transistors configuration based on a biphenyl end capped fused bithiophene oligomer (BPTT) and copper phthalocyanine (CuPC) were prepared. The measured maximum responsivity and the ratio of photocurrent to dark current (IPh/IDark) in BPTT and CuPC OPTs were 82 A/W, 2 A/W and 2.0 × 105, 1000 under 365 nm UV light with 1.55 mW/cm2, respectively. The prepared OPTs showed a photocurrent response similar to the photo to current conversion efficiency (IPCE) spectrum of BPTT and CuPC. The main mechanisms responsible for photocurrent amplification in the devices were examined by comparing theoretical and measured data. The photovoltaic (turn-on) and photoconductive effect (turn-off) of the OPTs were determined by fitting to theoretical equations. The findings confirmed that the operation of the OPTs followed as photo-voltaic (turn-on state) and photo-conductive (turn-off state) behaviors.
A new fully functionalized photorefractive polyimine was prepared by the condensation polymerization between a photoconducting carbazole derivative, 9-(2- ethylhexyl)carbazole-3,6-dicarbaldehyde, and a nonlinear optical stilbene chromophore, 4-[N,N-bis(2- aminoethyl)amino]-4'-nitrostilbene. It showed excellent solubility in common organic solvents such as chloroform, cyclohexanone, tetrahydrofuran, etc. and high optical quality films were obtained by free standing film casting. Very high second order optical nonlinearity with d33 equals 120 pm/V was observed by second harmonic generation at the fundamental 1064 nm wavelength. In demonstrated good thermal stability of the aligned dipoles by electric field up to ca. 125 degrees C. The diffraction grating was formed by the interference of two coherent Ar-ion laser beam at the wavelength of 488 nm. A holographic diffraction efficiency of about 15 percent has been achieve din a 10 micrometers -thick film. Storage state of our film shows remarkably long stability at room temperature.
We observe a new electroluminescent (EL) peak from a two-layer polymer device, which does not appear in EL spectra of each layer. The polymers of both layers are poly(p- phenylenevinylene) derivative with monoalkoxy substituents, poly(2-methoxy-1,4-phenylene- vinylene, abbreviated as PMPV), but dialyzed for different periods respectively. A new peak is located at 590 nm and has comparable intensity. The origin of this peak is discussed. Absorption and photoluminescence spectra are also measured and device properties show typical diode characteristics.