Poly(4,4´-diphenylene diphenylvinylene) Langmuir Blodgett thin films as a hole transport layer in polymer light emitting diode

Polymer based light emitting diodes (LED) are potentially useful in display technology. The basic structure of this device consists of a hole transport layer (p-type) and an electron transport layer (n-type). This paper reports a study on poly(4,4´-diphenylene diphenylvinylene) (PDPV) thin films for a hole transport layer in the device. The multilayer PDPV films were deposited on glass and ITO-covered glass substrates using the Langmuir Blodgett (LB) technique. Aluminum was deposited on the PDPV film as an electron injector and also as the electrode. The film was characterized by measuring the electrical properties, optical absorption and topography image. The sheet resistance of the PDPV film deposited on glass was (6.3±0.1)×10⁸ Ω per square and the energy gap of the film was 2.95±0.01 eV. The performances of the devices with ITO/PDPV/Al structure were studied through the current-voltage curves measured in the dark. It was found that the device showed typical diode properties