Rational Molecular Design Enables Efficient Blue TADF−OLEDs with Flexible Graphene Substrate

Observation of thermally activated delayed fluorescence (TADF) in conjugated systems redefined the molecular design approach to realize highly efficient organic light emitting diodes (OLEDs) in the early 2010s. Enabling effective reverse intersystem crossing (RISC) by minimizing the difference between singlet and triplet excited state energies (ΔEST) is proven to be a widely applicable and fruitful approach, which results in remarkable external quantum efficiencies (EQE). The efficacy of RISC in these systems is mainly dictated by the first-order mixing coefficient (λ), which is proportional to spin-orbit coupling (HSO) and inversely proportional to ΔEST. While minimizing ΔEST has been the focus of the OLED community over the last decade, the effect of HSO in these systems is largely overlooked. Here, molecular systems with increased HSO are designed and synthesized by substituting selected heteroatoms of high-performance TADF materials with heavy-atom selenium. A new series of multicolor TADF materials with remarkable EQEs are achieved. One of these materials, SeDF-B, results in pure blue emission with EQEs approaching 20%. Additionally, flexible graphene-based electrodes are developed for OLEDs and revealed to have similar performance as standard indium tin oxide (ITO) in most cases. These devices are the first report of TADF based OLEDs that utilize graphene-based anodes

Nanomateryallerin fonksiyonlaştırılması ve çevresel iyileştirmede kullanımı.

Environmental pollution is a problem which is threatening living organisms and ecosystem with increasing rate every day. For decades, many studies have been done and experiments have been conducted in order to cure this serious danger. Organic pollutants in general is a big danger especially a group called Persistent Organic Pollutants (POPs) which are mostly originates from industrial and other man made sources are great danger. Among POPs, Polycyclic Aromatic Hydrocarbons (PAHs) are the most common ones. Therefore removal of PAHs from natural environment is a great concern. This study focuses on the synthesis and use of three nanocomposites which are 25% Fe3O4/MWCNT, 40% Fe3O4/MWCNT and 50%Fe3O4 /MWCNT, and then compare the synthesized materials PAH’s removal efficiency with MWCNT and f-MWCNT. Materials used for removal or remediation are varied. Among them Carbon nanotubes (CNTs) are the cheapest and commonly used one. To make them target oriented remediation material, surface activation is performed. Synthesized Fe3O4 nanocomposites were characterized by Transmission Electron Microscopy (TEM), Fourier-Transform Infrared Spectroscopy (FTIR), Vibrating Sample Magnetometer (VSM) and X-Ray Diffraction (XRD) instruments and it was clearly understood that Fe3O4/MWCNT nanocomposites were synthesized successfully. To revelation to the adsorption feature, Gas Chromatography-Mass Spectrometry (GC-MS) was used. . For the GC-MS calibration, naphthalene, acenapthalene, acenapthyne, fluorene, phenantherene and anthracene r2 values are 0,999, 0,998, 0,997, 0,999, 0,999 and 0,998, respectively. According to the results obtained, 40 mg of material was able to adsorb ∑6 PAH with an efficiency of 98% from the solution containing 0.1 ppm PAH in 50 minutes. It has been observed that the purification of the synthesized materials can be easily carried out with the aid of a magnet after adsorption process, because of their great magnetic property.M.S. - Master of Scienc

FEN BİLİMLERİ ENSTİTÜSÜ/LİSANSÜSTÜ TEZ PROJESİ

HAVA KİRLETİCİLERİ OLARAK POLİKLORLU BİFENİLLER (PCB

HAVA KİRLETİCİLERİ OLARAK POLİKLORLU BİFENİLLER

HAVA KİRLETİCİLERİ OLARAK POLİKLORLU BİFENİLLE

Okuma Stratejisi Eğitiminin Matematik Dersi Problem Çözme Becerisine Etkisi

Okuduğunu anlama becerisi, ana dili öğretiminde dört temel dil becerisinden biri olmakla birlikte yalnızca ana dilinin gelişmesinde değil diğer derslerin başarısında da oldukça önemlidir. Amacı, okuma stratejisi eğitiminin matematik dersi problem çözme becerisine etkisini belirlemek olan bu araştırmada, ön – son test kontrol gruplu yarı deneysel desen kullanılmıştır. Araştırma, ilgili yerlerden gerekli izinler alınarak 2017-2018 eğitim öğretim yılında, Ankara ilindeki bir devlet ortaokulunun iki 6. sınıf şubesiyle gerçekleştirilmiştir. Sınıf mevcudu, matematik ve Türkçe dersi akademik başarıları birbirine denk olan, Türkçe ve matematik derslerini aynı öğretmenlerin yürüttüğü iki 6. sınıf seçilmiş; yansız atama yoluyla sözü edilen sınıflardan biri kontrol, biri deney grubu olarak belirlenmiştir. Araştırmada, deney grubuna okuma stratejilerine göre hazırlanmış etkinlikler uygulanırken kontrol grubundaki dersler, ders kitabındaki etkinliklerle yürütülmüştür. Uygulama çalışması on haftada tamamlanmıştır. Araştırma sonucunda, okuma stratejisi eğitimi verilen deney grubu öğrencilerinin matematik dersi problem çözme başarı testi puanlarının kontrol grubu öğrencilerinin puanlarından daha yüksek olduğu belirlenmiştir. Deney grubu öğrencilerinin on haftalık uygulama sonrası matematik problem çözme becerilerinin geliştiği sonucuna ulaşılmıştır

Bistriphenylamine- and benzodithiophene- based random conjugated polymers in ternary blend bulk heterojunction organic solar cells

Concept of Ternary organic solar cell is one of the most promising topics in photovoltaic studies. However, because of the complicated phase separation systems, improving the power conversion efficiency is quite compelling. In this study, a ternary organic solar cell with two donors Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3- fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and benzodithiophenebased random conjugated polymers (P1 and P2) and one fullerene based acceptor (PC71BM) are used to form the active layer. Two donors are complementary with each other in the UVVIS spectra, in other words, λmax values of PTB7 and P1 were determined as 760 nm and 481 nm, respectively. Photovoltaic performance of the polymers P1 and P2 were examined under the illumination of AM 1.5G, 100 mW.cm-2. Photovoltaic studies showed that the highest power conversion efficiency of these photovoltaic devices were recorded as 3.50% with open circuit voltage; 0.79 V, short circuit current; 9.45 mA.cm-2, fill factor; 0.53