The Research On Low Power Organic Light Emitting Diode Technology

Organic light emitting diodes (OLEDs) have been changing the markets of flat-paneldisplay and general solid-state lighting due to their remarkable developments during thepast two and a half decades. In order to cultivate OLEDs into one leading pillar of themodern industry in the near future, the tremendous efforts are desired to advance thetechnologies of OLEDs towards the practical levels that inorganic LEDs are approaching.In particular, it is of significance to optimize the power efficiency and consumption ofOLEDs, relying on the prospective breakthroughs in the design and physical thought ofdevice structure. This thesis mainly do the four aspects of the research work:Firstly, Inverted bottom OLEDs using the PEDOT:PSS/Li2CO3:BCP heterojunction inelectron injection have been fabricated. The efficient electron injection from PEDOT:PSSto Li2CO3:BCP was discussed based on the Fermi level alignment across organicheterojunction. Also, the electrical reduction of PEDOT+to PEDOT0was suggested toexplain the independence of the device performance on the PEDOT:PSS thickness.Secondly, in order to reduce the hole loss during the process of the hole transport intothe NPB so as to achieve high-performance OLEDs, two p-doped hole transport layersusing the NPB:MoO3/CBP: MoO3in OLEDs have been fabricated. We demonstrate thatthe structure of uniting two p-doped hole transporters is a beneficial, simply method ofachieving the improved trade-off between the high conductivity and small hole transportbarrier, thereby leading to the significantly reduced ohmic loss in the hole currentconduction in the OLEDs, relative to the single p-doped layers.lastly, the doped reverse p-n heterojunction may function as an efficient CGL structure.So the CGLs will be optimized by the usage of higher-conductivity p-HTL, because theycan reduce the ohmic losses in the current conduction through the CGLs. We fabricate thecharge generation layer (CGL) structure comprising of BCP: Li2CO3/5nm NPB:MoO3/15nm CBP: MoO3for tandem organic light emitting diodes (TOLEDs). Compared tothe TOLED using the conventional CGL structure of BCP: Li2CO3/20nm CBP: MoO3, thestructure showed increased electrical and luminous properties.