导电聚合物作为连接层的叠层电致发光器件

Organic stacked light-emitting devices based on PEDOT:PSS layer

有机电致发光器件(OLED)因具有全固态、主动发光、高色域、视角宽、非常轻薄和可折叠卷曲等优点,被认为是可取代液晶显示的技术之一.但是,由于这种器件使用的有机材料很容易与空气中的水和氧气发生反应,并且其玻璃化温度比较低,导致器件稳定性和效率比较低.因此通过某种方式提高器件的电流效率、减少器件的发热功耗,降低器件的运行电流,具有非常重要的意义.叠层(Stacked)器件结构技术是实现低电流、高效率OLED的一种有效途径.但是,如何利用简单的方法制作高效的叠层器件连接层,使电流高效地通过器件,是研制这种器件的重要挑战.本文利用PEDOT:PSS作为器件连接层,成功制备出结构为ITO/PEDOT:PSS(15 nm)/PFO(80 nm)/PEDOT:PSS(40 nm)/PFO(80 nm)/Al(70 nm)的叠层有机电致发光器件.通过研究叠层器件的电流-电压特性、电压-亮度特性和电流-效率特性发现,在未做任何特别优化的条件下,该叠层器件的启亮电压为12.3 V,启亮电流为1.39μA.电流效率(3.97 cd/A)是单层对比器件电流效率的8倍.更为重要的是,这种PEDOT:PSS新型叠层器件连接层既不需要高温蒸发镀膜也不需要掺杂.该方法既简化了Stacked叠层器件连接单元的制备工艺,避免了高温蒸镀对器件膜层的损伤,又克服了现有掺杂工艺原子散射对器件性能破坏的难题.同时,本文对PEDOT:PSS作为叠层有机电致发光器件连接层的物理机制进行了探讨.

Organic light-emitting devices(OLEDs)have been the intensive investigation subject in recent years due to their applications in lighting and displays.The typical OLED structure usually consists of a transparent indium-tin-oxide bottom anode,a top metal cathode,and some organic layers sandwiched between electrodes.After 30 years of unremitting efforts,the performance of OLEDs has been close to the level of inorganic semiconductor light-emitting devices.However,in order to achieve the final application goal of dynamic panchromatic HD display,the luminous efficiency and stability of the device need to be further improved.Especially because organic materials are not resistant to high temperature,improving the luminous efficiency of the device and reducing the heat loss become the key to improving the stability and service life of the device.One of the important factors that affect the life of OLEDs is the thermal aging caused by the high current flowing through it.Therefore,it is of great significance to study a kind of high efficiency device operating at low current.Stacked device structure technology is an effective way to realize low current and high efficiency OLEDs.The major challenge in stacked OLEDs in general is to prepare the effective connecting layer between emitting units so that the current can smoothly flow through without manufacturing difficulties.In this paper,we use PEDOT:PSS as the connecting layer of the device,and successfully prepare the stack organic lightemitting device with ITO/PEDOT:PSS(15 nm)/PFO(80 nm)/PEDOT:PSS(40 nm)/PFO(80 nm)/Al(70 nm)structure.By studying the current-voltage characteristics,voltage-brightness characteristics and current-efficiency characteristics,it is found that the illumination voltage and the illumination current are 12.3 V and 1.39μA,respectively.The current efficiency(3.97 cd/A)is 8 times higher than that of single-layer comparator.The connection layer of this new type of PEDOT:PSS stack device needs neither high temperature evaporation coating nor doping.This method not only simplifies the preparation process of the connection unit of the stacked device,avoids the damage of the device film caused by high temperature evaporation,but also overcomes the problem of the damage of the device performance caused by the atomic scattering of the existing doping process.At the same time,the physical mechanism of PEDOT:PSS as the connecting layer of stacked OLED is discussed.