Influence of thickness of electrochemically deposited hole-transport film on electroluminescent properties

Polybithiophene (PBTh) film was used as a hole-transport layer in an electr oluminescent (EL) device. The PBTh was electropolymerized on indium tin oxi de (ITO)coated glass acting asa working electrode. From the change of full width at half maximum (FWHM) of the EL spectrum with the thickness of the P BTh film, it could be deduced that the PBTh film efficiently blocks the inj ection of electrons into the ITO electrode. The thickness of the hole-trans port layer used in the EL device has a significant influence on the EL inte nsity and efficiency. Experimental data showed that there is an optimal thi ckness of the electrodeposited PBTh-hole-transport layer for high-efficienc y EL devices. PACS: 73.50.-h; 73.61.-r; 73.61.Ph.