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AIP Conference Proceedings [AIP Publishing 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Bikaner, India (14a??15 October 2019)] 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Computational study on 8-quinolinolato-alkali, an electron transporting material for OLED devices
摘要： Organic light-emitting diodes (OLEDs) materials have occupied significance in device applications due to their lightweight, thin, quick switching speed, flexible, easy to fabricate and low-cost features. The 8-quinolinolato-lithium (Liq) is commonly used as an electron injector in the layer of OLEDs. Herein, we study 8-quinolinolato-sodium (Naq) and 8-quinolinolato-potassium (Kq) and compare them with Liq using density functional theory approach. We analyze the molecular structure of 8-quinolinolate-alkali (Mq) for M = Li, Na and K and notice that the structure of Mq remains planar for all the three substitutions. The increased dipole moments of Mq with the change of substitution (M) suggest that its enhanced solubility in polar solvents, which tends to reduce the electron injection barrier. Furthermore, the higher polarizability of Naq and Kq indicates that the molecule is chemically more reactive than Liq and therefore, is expected to respond quickly when the field is applied. Moreover, the electron affinities of Mq increase with the substitution of Na and K, which is also desirable for improved electron transport behavior. However, the reorganization energy of Naq and Kq is slightly higher than that of Liq, which is not desirable for the transport of charge carriers in OLED devices. Therefore, the findings of this study demand further assessment for the application of Naq and Kq instead of Liq in OLED devices.
关键词： electron transporting material,8-quinolinolato-alkali,density functional theory,OLED
更新于2025-09-23 15:21:01
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Combustion-processed NiO/ALD TiO2 bilayer as a novel low-temperature electron transporting material for efficient all-inorganic CsPbIBr2 solar cell
摘要： Low-temperature ALD TiO2 electron transporting layers (ETLs) are promising for all-inorganic perovskite solar cells (PSCs), such as the CsPbIBr2-based ones. However, the non-ideal interfacial level-alignment between ALD TiO2 and CsPbIBr2, as well as the concomitant defects in ALD TiO2 during preparation of upper CsPbIBr2 film severely limit the performance of final PSC. We report herein a new design of ETL by combining ALD TiO2 with low-temperature combustion-processed NiO. Although the underlying NiO layer has a p-type conductivity and is known as a hole transporting layer (HTL), the NiO/ALD TiO2 bilayer can serve as an ETL with fewer traps, larger conduction band minimum (CBM) offset with CsPbIBr2 film, along with the similar optical transmittance, in contrast with individual ALD TiO2 ETL. Consequently, the resulting optimized CsPbIBr2 PSC yields the superior efficiency of 9.71% and photovoltage of 1.272 V, both of which exceed those of the one based on individual ALD TiO2 ETL and even so-gel TiO2 ETL. Our work verifies the great applicability of NiO/ALD TiO2 ETL for CsPbIBr2 PSC and thereby explores a promising way to develop more low-temperature ETLs by combining conventional HTLs with ALD TiO2 layers.
关键词： NiO/TiO2 bilayer,ALD,Low temperature,All-inorganic CsPbIBr2 solar cells,Solution combustion,Electron transporting material
更新于2025-09-23 15:19:57
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Spirobifluorene-based oligopyridine derivatives as electron-transporting materials for green phosphorescent organic light-emitting diodes
摘要： The electron-transporting materials (ETMs), 2,7-bis(3,5-di(pyridin-3-yl)phenyl)-9,9'-spirobi[fluorene] (3-4PySF) and 2,7-bis(3,5-di(pyridin-4-yl)phenyl)-9,9'-spirobi[fluorene] (4-4PySF) were designed and synthesized by combining spirobifluorene moiety with di(pyridine-3-yl)phenyl and di(pyridine-4-yl)phenyl, respectively. The spirobifluorene moiety improves materials’ rigid twisted structure to ensure the morphological stability of amorphous film, and pyridine acts as electron acceptor to enhance electron-transporting ability of materials. The dependence of electron-transporting property on the position of substituted pyridine rings was studied. The melting point (Tm) of 4-4PySF is estimated to be 41 ℃ higher than that of 3-4PySF. And the higher current density in the electron only devices exhibited by 4-4PySF revealed the effect of nitrogen atom position on the charge-transporting properties. Green PhOLEDs based on bis(2-phenylpyridine)iridium(III)(2,2,6,6-tetramethylheptane-3,5-diketonate) (Ir(ppy)2tmd) as the emitter and 3-4PySF, 4-4PySF and 1,3,5-tris(N-phenylbenzimidazol-2-yl-benzene (TPBi) as ETMs were fabricated. Compared to the device based on the conventional ETM TPBi, the devices based on new ETMs exhibited a higher maximum external quantum efficiency (EQE) of 20.5% and a lower turn-on voltage (Von) of 2.6 V.
关键词： electron-transporting material,intermolecular interaction,oligopyridine,organic light-emitting diode,spirobifluorene
更新于2025-09-19 17:13:59
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Corea??twisted tetrachloroperylenediimides: lowa??cost and efficient nona??fullerene organic electrona??transporting materials for inverted planar perovskite solar cells
摘要： In this work, we introduced the core-twisted tetrachloroperylenediimides (ClPDIs) as new efficient electron-transporting materials (ETMs) to replace the commonly used fullerene acceptor (PC61BM) in inverted planar perovskite solar cells (PSCs). The ClPDI shows a low-lying LUMO energy level of -3.95 eV, which is compatible to the conduction band of MAPbI3-XClX (-3.90 eV). In addition, we investigated the role of the alkyl side chain length at the imide position on ClPDI in modulating the molecular solubility, aggregation capacity for charge transport properties, surface hydrophobicity and perovskite solar cell performances. The device based on ClPDI-C4 (ClPDI with n-butyl side chains) as ETM achieved a maximum power conversion efficiency (PCE) of 17.3% under the standard AM 1.5G illumination, which is very competitive to the reference device employing PC61BM/C60 (PCE= 17.2%) as ETM. Moreover, the devices with ClPDIs as ETMs exhibit better device stability than that with PC61BM/C60. This work highlights the great potential of ClPDI derivatives as the low cost (~2.0 USD per gram) and efficient ETMs to achieve efficient solution-processed inverted PSCs. We believe this class of ClPDI derivatives that will further promote the performance and stability of PSCs after extended investigation.
关键词： perovskite solar cells,electron-transporting material,perylenediimide,non-fullerene
更新于2025-09-19 17:13:59
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Starburst-type triarylphosphine oxide trimers forming a stable amorphous n-type layer in solution-processed multilayer OLED
摘要： Novel starburst-type triphenylphosphine oxide trimers PO-1 and PO-2 were synthesized aimed at application as an electron-transporting material for multilayer organic light-emitting diodes (OLEDs). They showed high glass transition temperatures (Tg; 175 and 205 (cid:1)C, respectively) and high lowest triplet energies (T1; 2.81 and 2.78 eV, respectively). Their high solubility in 2-propanol allowed us to fabricate multilayer OLEDs by solution processing, and a double-emitting layer OLED consisting of poly(9-vinylcarbazole)-based p-type and PO-1-based n-type layers doped with a phosphorescent material (FIrpic) showed efficient sky-blue electroluminescence with a maximum external quantum efficiency of 9.33%.
关键词： Solution processing,Organic light-emitting diode,Phosphine oxide,Double emitting layer,Multilayer,Electron-transporting material
更新于2025-09-16 10:30:52
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The Effect of SnO2 and ZnO on the Performance of Perovskite Solar Cells
摘要： The efficiency of perovskite solar cells is studied through the Analysis of Microelectronic and Photonic Structures (AMPS) and the Solar Cell Capacitance Simulator (SCAPS) simulation software programs. The programs serve to determine how the thickness of HTM, ETM and perovskite absorber layers affects the performance of solar cells. An investigation is also conducted on how temperature, electron density concentration and perovskite defect density affect the fill factor (FF), performance (PCE), short-circuit current density (JSC), and open-circuit voltage (VOC). Then, J–V characteristics are calculated using ZnO and SnO2 as two types of ETM. As a result, optimal values are achieved for the thickness of HTM, ETM and absorber layers. It is also indicated that an increase in the defect density of perovskites can reduce the performance of solar cells. Another important finding of the study is that ZnO can possibly replace the expensive SnO2 for better ETM conversion performance.
关键词： electron-transporting material,AMPS,Perovskite solar cells,SCAPS
更新于2025-09-12 10:27:22