Fabrication And Properties Of Devices Containing Near Infrared Electroluminescent Materials Based On Cyclometalated Platinum(?) Complexes

In recent years,the research of near-infrared organic light-emitting diodes(NIR-OLED)has become one of the important development directions due to their special applications in night vision,medical,communication and other fields.Furthermore,enormous researches based on transition metal complexes has received extensive attention,due to the strong spin-orbit coupling(SOC)can achieve an internal quantum efficiency(IQE)to 100%.This paper introduces the working mechanism of organic electroluminescent devices and the research status of near-infrared organic electroluminescent materials and devices.But there are many problems with solution-processed NIR-OLEDs at present,such as low luminous efficiency,high turn-on voltage and serious roll-off of efficiency.In order to solve these problems,this paper reported a near-infrared electroluminescent material device based on cyclometalated complexes are performance studies,and we have studied the interaction between host and guest in the light-emitting layer,and achieved the balance of carrier transport in the device by optimizing the device structure for each functional layer.The main research contents of this paper are as follows:1)In this chapter,the design and optimization process of the host is carried out,which based on the cyclometallic binuclear platinum complex(BIQPy)[Pt(DPM)]₂.Near-infrared electroluminescence devices with different host materials were obtained separately,including small molecule host CBP,exciplex host m-CBP:PO-T2T and polymer host PVK.As a result,all of the solution-processed NIR-OLEDs based different hosts are observed in the stable electroluminescent(EL)emission around of 700 nm.And the maximum EQE and radiant emittance were obtained to be 0.88%/9159 m W/Sr/m²,1.27%/4999m W/Sr/m² and 6.06%/24259 m W/Sr/m² for the CBP,m-CBP:PO-T2T and PVK host device,respectively.2)The carrier transport characteristics and energy transfer mechanism are greatly affected by changing the functional layer structure of the electron transport layer,hole transport layer and electron blocking layer in the device based on the binuclear platinum complex(Th Py IQ)[Pt(DPM)]₂.As a result,the devices based on Tm Py Pb as the electron transport layer exhibit a maximum EQE value of 0.69%and a radiant emittance of 3968 m W/Sr/m² at a dopant concentration of 1 wt%.And the maximum EQE and radiant emittance were obtains to be 0.95%and 4046 m W/Sr/m² for the device based on TAPC as the hole transport layer,respectively.Encouragingly,the devices based on a hole transport layer(TAPC)and a hole blocking layer(DPEPO)are observed an stable emission of 708 nm with best EQE of 1.31%and a radiant emittance of3968 m W/Sr/m².