Charge conduction process and photovoltaic properties of a N,N′-di-benzyl 4,4′ bipyridyl dichloride based Schottky device

Abstract

Charge conduction process and photovoltaic characteristics of N,N′-di-benzyl 4,4′ bipyridyl dichloride (DBD) based thin film Schottky device were investigated. The conduction mechanism is explained on the basis of modified Schockley equation and through the J–V characteristics under bias voltage ranging from 0.8 to 1.2 V. The space charge limited current (SCLC) region seems to be predominant beyond 1.2 V whereas below 0.8 V the Schottky emission or Poole–Frenkel emission appears to be effective in transportation of current. Impedance analysis was also carried out to ascertain the existence of the Schottky barrier at In–DBD interface. The temperature dependent ac conductivity reveals the predominance of hopping conduction in DBD thin films. The observed higher ideality factor, i.e., 1.65 can be attributed to the high interface resistance leading to low electron mobility and accelerated recombination of electron and hole at In–DBD junction. The photogeneration mechanism of the charge carriers in the device has also been described in detail. The analysis of SCLC at high voltage region and exponential relation of the photocurrent with illumination intensity attributes an exponential trap distribution in the band gap of the film.