Effect Of Exciton Adjusting Layer On The Performance Of White Organic Light-Emitting Devices

Organic light-emitting device(OLED)has entered the commercialization stage with the continuous development in the past three decades.Due to its advantages of wide viewing angle,high brightness,fast response,light and thin,it has received extensive attention in the lighting display field.At present,most of methods for fabricating white OLEDs are realized by synthesizing novel materials or doping.Doping is to form a host-guest doped structure by embedding the guest luminescent material into the host material by hybrid evaporation.Due to the inaccurate doping ratio,the repeatability of devices obtained by the experimental preparation is poor.The product yield is also not high,resulting in a relatively high cost.As a result,it is not suitable for commercial production of OLEDs.This dissertation mainly focuses on the exciton adjusting of double ultrathin light-emitting layer white OLED devices.The exciton adjusting layer is embedded into the double ultrathin light emitting layer.So,the excitons can be appropriately distributed in the double ultrathin light emitting layer to realize a dual color complementary white OLED device.The device structure is relatively simple and easy to prepare.The specific research content of this paper is as follows:(1)By selecting the organic semiconductor material mCP as an exciton adjusting layer(EAL),the EAL devices of different thicknesses are fabricated.The influence of the thickness of the mCP layer on the distribution of carriers and excitons is analyzed.The relationship between the thickness of EAL and the spectrum was explored,from which it was concluded that a suitable thickness of EAL is beneficial to inhibit the direct recombination of carriers in the yellow light layer.And the stability of the spectrum can be promoted when the applied voltage changes.Among them,the devices based on 4nm thick EAL show stable Commission Internationale de L'Eclairage(CIE)color coordinates,from a brightness of 124 cd/m~2(0.32,0.40)to a brightness of 9705 cd/m~2(0.30,0.40).(2)Four kinds of organic materials are used as exciton adjusting layers,respectively.When the four devices realize white light,the efficiency and electroluminescence(EL)spectrum of the devices can be used to discover the carrier transport and EL mechanism of the white organic light-emitting device(WOLED).The results show that different EL spectra can be obtained by selecting the thickness of the EAL.At the same time,it is found that the triplet energy level and carrier mobility of EAL play an important role in the exciton transmission of WOLED.This study has a reference value for adjusting the distribution of carriers and excitons in a double ultrathin light-emitting layer WOLED,and it can also be used in future WOLED devices.In summary,in this thesis,a high-efficiency white OLED device consisited of an ultrathin light-emitting layer was realized by embedding an exciton adjusting layer into a double ultrathin light-emitting layer.By comparing and analyzing different thicknesses of the same material with different materials in the device,the influence of exciton-controlled device on the performance provides a reference value for the subsequent research on double ultrathin light-emitting layer OLED devices.