Organic small molecule and polymer luminescent materials have shown great potential for commercial application of organic light-emitting diodes (OLED)

due to their high luminescent level and quantum efficiency.With the development of OLED more and more attentions were attracted to improve their efficiency.Because excitons are strongly confined for molecular semiconductors

the relative spin configuration of injecting electron (spin 1/2) and hole (spin 1/2) determines the excited state properties (singlet or triplet).Radiative decay from singlet exciton is fast and that from triplets is spin-forbidden.and.often very inefficient

but triplet emission is partially allowed in the presence of spin-orbit coupling and can be seen in molecule containing elements of high atomic number.The use of triplet emitters to improve OLED efficiency has already been proposed.Up to date

most center metal atoms are rare metals such as Pt

Ir

Ru

Re

Os etc.

but it is essential for people to find some cheaper ones to realize efficient EL emission and to decrease the cost of OLED.Cu

4

displays intense emission at 520nm with a quantum yield of 0.42 in-dichloromethane.Here we reported the results of devices using a blend film of Cu

4

and the hole transport polymer PVK as the emitting layer.The structure of this device is ITO/Cu

4

: PVK/TAZ/Mg/Al and it can realize the emission of triplet Cu

4

at 516nm.The research focused on energy transfer especially on EL process and the influence of oxygen on the photoluminescence of Cu

4

.