Charge transport, injection, and photovoltaic phenomena in oligo(phenylenevinylene) based diodes

We report on the charge transport and injection phenomena of ( E , E , E , E )‐1,4‐bis[(4‐styryl)styryl]‐2‐methoxy‐5‐(2′‐ethylhexoxy)benzene (MEH‐OPV5) sandwiched between asymmetric contacts. The hole mobility of MEH‐OPV5 was determined by means of transient electroluminescence. The steady‐state current was injection‐limited. The electric field and temperature dependence of the current were quantitatively described by a phenomenological injection model of thermally assisted charge‐carrier tunneling in a one‐dimensional chain of hopping sites. Furthermore, we report on the photovoltaic properties of thin‐film photovoltaic cells on the basis of donor–acceptor heterojunctions. MEH‐OPV5 and buckminster fullerene were used as the donor and acceptor materials, respectively. The emphasis was on the role of morphology in such devices.