Organic Light-emitting Exciplex Formation In The Device And Its Applications

Organic electroluminescent (OEL) devices are one of hot research project because of great interests in both science and applications among photoelectronic field. People invent a series of luminescent materials and devices, but the emission from exciplex is usually found in OEL devices. The color of devices is disturbed badly and the luminescent efficiency of devices is degradated because of exciplex's emission. The mechanism is investigated in this paper on the formation of exciplex and on the mixing-layer device structure eliminating the exciplex based on rare-earth complex, specially on Eu(DBM)3bath and Gd(DBM)3bath. It is thought that the exciplex results from the interaction between the singlet excited state of the ligand of electron acceptor material and the ground state of electron donor material. It is thought that the exciplex's emission is eliminated completely by modulating the transient excited state of exciplex thought varying the ratio of two molecules and by action from the excited state level of rare-earth ions. Furthermore, it is found that exciplex from the devices based on small molecule material, such as Alq3, can not be eliminated through the mixing-layer structure but other methods such as through blocking.Generally, the photovoltaic properity in devices with pure emission color is poor and the emission color in devices with good photovoltaic properity is not pure. Based on a binuclear complex, (Eu0.5Gd0.5XDBM)3bath, used as luminescent material in this paper, the device with pure narrow emission and good photovoltaic properity is fabricated.