The Studies On OLED Based On Exciplex

Since C.W.Tang reported the first organic light emitting diodes(OLEDs)with two layers in 1987,the technique of OLED has developed into practical application and attracted tremendous public attention.The OLED screen has commercialized,which is in evaporation deposition method with high cost and low utilization of materials.And it is hard to fabricate the 55-inch OLED panels in evaporation deposition method.By contrast,the inkjet printing is a new material additive manufacturing way for large-area OLED fabrication with low cost.The OLED devices based on exciplex have advanges of low drive voltage,high efficiency,and adjustable energy level by different donors and acceptors.The combination of exciplex and inkjet printing method is benefitial to industrializiton of OLEDs with low cost and high performance.This paper is focused on the design and mechanism of exciplex OLED,and its application in inkjet printing,including the following parts:1.TAPC and T2T are selected as donor and acceptor,respectively.The green OLED device based on exciplex shows high external quantum efficiency(EQE)of 11.6%.Because of short exciton life,the roll-off of device is only 19%from the maximum efficiency to a high luminescence of 1000cd/m2.2.Based on part 1,the PO-T2T and 3P-T2T with the similar molecule structure of T2T are chosen as acceptors.It is found that the photoluminescence quantum yield(PLQY),exciton life and charge carrier balance play an important role in the exciplex OLEDs.And it establishes foundation to the efficient OLEDs based on exciplex.3.The hole transporting ink includes 75%ethylene glycol and 25%PEDOT:PSS(VPAi 4083,Heraeus),which is suitable for hole transporting layer printing.The well soluable mCP and TPBi are selected as donor and acceptor,and Ir(mppy)3 is used as phosphorescent dopant.The solvents of emitting layer ink consist of butyl benzoate and CB.The double layer printed OLED has achieved with 3.2%EQE.And the single layer printed OLED exhibits the EQE of 6.7%,which is very close to the spin-coating one with the same structure.4.The pixel arrays are fabricated by photoetching on ITO glass.The pixel OLED devices have been achieved by means of adjusting the pattern,drive voltage and annealing process,which is meaningful for inkjet printed OLED panels.