Organic electronics offers several advantages as compare with inorganic technology, such as lightweight, large area, flexibility or conformability of electronic devices. Additionally, if organic electronics is based on solution processable materials, it should allow to employ cheap and energy-saving printing techniques for mass fabrication of very broad range of electronic components [1]. Among them printable organic light emitting diodes (OLEDs) attract a special attention since the OLEDs fabricated by vacuum deposition technology are already applied on large scale in displays and monitors since many years. However the technique of printing OLEDs cannot overcome laboratory scale and in fact in most published reports, only one or two layers in these devices are printed, while the rest are deposited by vacuum evaporation technique. This is due to a number of serious obstacles hindering possibility of fabrication by means of solution based techniques and with high precision multilayer OLED structures [1, 2]. 

In this talk we will analyse the most important problems, which are still not fully solved, such as low efficiency of OLEDs due to difficulties in employing triplet states, lack of proper printable interlayers, allowing to facilitate injection of one sign charge carriers and to block charge carriers of opposite sign, technical problems with producing multilayers structures, lack of conducting inks, compatible with active organic layers, poor precision and low resolution of available printers, and lack of flexible, transparent and highly efficient barrier materials. In the Department of Molecular Physics of Lodz University of Technology we are involved since several years in research aiming to solve the most critical issues related to printed organic electronics and we will present selected results illustrating application of new solution processable active layers exhibiting electrophosphorescence or thermally delayed fluorescence (TADF), printable interlayers and electrodes, as well as our approach for ink formulation and high precision printing technique [3, 4, 5]. These results will be used as a base for presentation of future research plans and perspectives for developing technology of fully printable OLEDs.