Багатошарові нанорозмірні світловипромінювальні структури видимого та ультрафіолетового спектра на основі модифікованих карбазолів

Abstract

Дисертаційна робота присвячена вирішенню проблем розроблення багатошарових нанорозмірних світловипромінювальних структур (ОСВС) видимого та ультрафіолетового спектра на основі модифікованих карбазолів для пристроїв відображення інформації чи джерел світла. Розроблено багатошарові нанорозмірні ОСВС фіолетового (0,19, 0,05) та синього (0,14, 0,06) кольорів; білого кольору з колірними координатами (0,36; 0,38); вертикальна трьохлектродна ОСВС з вбудованим електродом у світловипромінювальний шар в область формування ексиплексу, яка уможливлює керування кольором свічення від координат синього (0,15; 0,22) до оранжевого (0,51; 0,47) кольору; фосфоресцентні багатошарові нанорозмірні ОСВС оранжевого (0.65, 0.35), червоного (0.53, 0.47) та синьо-зеленого (0.23, 0.44) кольорів; ОСВС зеленого кольору з уперше створеними для неї оптично прозорими електродами на основі нелегованого оксиду цинку з використанням методу атомно-пошарового нанесення; електрофлуоресцентні ОСВС синього кольору на основі серії модифікованих похідних карбазалу. многослойных наноразмерных светоизлучающих структур (ОСВС) видимого и ультрафиолетового спектра на основе модифицированных карбазолов для устройств отображения информации или источников света. Разработаны многослойные наноразмерные ОСВС фиолетового (0,19, 0,05) и синего (0,14, 0,06) цветов; белого цвета с цветовыми координатами (0,36; 0,38); вертикальная трехэлектродная ОСВС с встроенным электродом в светоизлучающий слой в область формирования эксиплекса, позволяющая управлять цветом свечения от координат синего (0,15; 0,22) до оранжевого (0,51; 0,47) цвета; фосфоресцирующие многослойные наноразмерные ОСВС оранжевого (0.65, 0.35), красного (0.53, 0.47) и сине-зеленого (0.23, 0.44) цветов; ОСВС зеленого цвета с впервые созданными для нее оптически прозрачными электродами на основе нелегированного оксида цинка при использовании метода атомно-послойного нанесения; электрофлуоресцентные ОСВС синего цвета на основе серии модифицированных производных карбазалау. The thesis is devoted to the development of nanoscale multilayer visible and ultraviolet spectra light-emitting structures (OLES) for displays or light sources which are based on modified carbazole. Purple and blue nanoscale multilayer OLES; white OLES (color coordinates of (0.36, 0.38)); a three-terminal device with an embedded metallic layer (middle electrode) in the region of exciplex formation which demonstrate the possibility of color tuning in a wide spectral range from blue (0.15, 0.22) to orange (0.51, 0.47); orange (0.65, 0.35), red (0.53, 0.47) and blue-green (0.23, 0.44) phosphorescent multilayer nanoscale OLES; green OLES with optically transparent electrodes created for it based on doped zinc oxide using the method of atomic layered deposition; OLES blue through a series of modified derivatives carbazole were developed. First, highly efficient violet and blue organic electroluminescence devices were fabricated. They exhibit high current efficiency of 5.3 and 13.5 cd/A, high brightness of 3458 and 12535 cd/m2 and high external quantum efficiency of 5 and 17%, respectively. Such high efficiency of the fabricated devices is due to the efficient spin up-conversion from nonradiative triplet states of the host to the radiative singlet states of the guests. Second, carbazole derivativce THCA and TBPCA were used for the fabrication of OLEDs. The electroluminescence spectra of single-layer OLEDs are similar the to photoluminescence spectra of the vacuum deposited films of THCA and TBPCA and are characterized by one well-defined narrow peak at 465 and 470 nm, respectively. Broad red-shifted bands observed in the electroluminescence spectrum of the bilayer devices (THCA/Alq3 and TBPCA/Alq3) can be attributed to the exciplex emission that occurs in the interface of THCA (TBPCA) and Alq3. A new technological approach for the preparation of white OLED (WOLED) is proposed. The approach is based on a combination of distributed blue (exciton) and orange (exciplex) electroluminescence in one device, which is in fact a parallel connection of many single- and double-layered discrete OLEDs. The brightness of WOLED at 7 V is 300 cd/m2 with current efficiency 2.3 cd/A. Third, 3,6-Bis(indol-1-yl)-9-phenylcarbazoles were tested in the single-layer organic light emitting diodes as active materials and in phosphorescent light emitting diodes as host materials of emitting layers in the combination with Ir(Fppy)3 as a guest phosphor. The maximum brightness of the fabricated single-layer electroluminescent devices was ca. 1000 cd/m2 with the current efficiency of 4.0 cd/A and that of electrophosphorescent devices was ca. 11,000 cd/m2 with current efficiency of 12.2 cd/A. Single-layer PhOLEDs were fabricated employing a simple technological approach, based upon the simultaneous vacuum deposition from one crucible of the host material CBM4 and a phosphorescent 1,2,3-triazole-based iridium complex. The maximum brightness of the obtained PhOLEDs is about 6000 and 10,000 cd/m2 with the current efficiency 5.3 cd/A and 6.8 cd/A for the devices with IC1 and IC2 respectively. These characteristics are quite high, taking into the account the absence of any additional injection and transport layers in the constructed PhOLEDs. Finally, the properties of anode contacts in OLED structure obtained by the ALD method using not intentionally doped ZnO films were demonstrated. The so obtained contact possesses good conductivity and optical transparence. The ZnO/CuI/Alq3/PEGDE/Al OLED device was fabricated showing brightness comparable to the best reported in literature for similar structures with Alq3 emitting layer. Impedance spectroscopy experiments unambiguously indicate the absence of energy barrier between anode and cathode interfaces. The device external quantum efficiency of 1.5% of the device was found better comparing to the analogous structure with ITO as anode contact. The advantageous properties of UV OLED structure containing indium-free transparent anode (ZnMgO:Al) and the layer of 2,7-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole as the light emitting layer were demonstrated. The obtained ZnMgO:Al contact does not low resistivity (~10-2 Ωcm) and is optically transparent from 325 nm. Depending on the growth conditions, semiconducting as well as highly conductive ZnO films can be grown by ALD. When having low carrier concentrations, ZnO films are active elements in hybrid organic–inorganic p–n junctions, which leads to higher rectification, higher forward currents and improved device stability compared to all organic or organic/metal structures.