scholarly journals Intramolecular and interfacial dynamics of triarylamine-based hole transport materials

2018 ◽  
Vol 17 (6) ◽  
pp. 722-733
Author(s):  
Johannes R. Klein ◽  
Mirko Scholz ◽  
Kawon Oum ◽  
Thomas Lenzer
Keyword(s):  
Light Harvesting ◽  
Hole Transport ◽  
Hole Injection ◽  
Interfacial Dynamics ◽  
Hole Transfer ◽  
Good Contact

Hole injection across interfaces is fast but critically depends on good contact between the hole transfer and light-harvesting materials.

scholarly journals A Study of Interfacial Electronic Structure at the CuPc/CsPbI2Br Interface

Crystals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 547
Author(s):  
Zengguang Tang ◽  
Liujiang Zhang ◽  
Zhenhuang Su ◽  
Zhen Wang ◽  
Li Chen ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Molecular Orbital ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Energy Gap ◽  
Hole Transport ◽  
Hole Injection ◽  
Band Bending ◽  
Valance Band Maximum ◽  
Interfacial Electronic Structure

In this article, CsPbI2Br perovskite thin films were spin-coated on FTO, on which CuPc was deposited by thermal evaporation. The electronic structure at the CsPbI2Br/CuPc interface was examined during the CuPc deposition by in situ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) measurements. No downward band bending was resolved at the CsPbI2Br side, whereas there is ~0.23 eV upward band bending as well as a dipole of ~0.08 eV identified at the molecular side. Although the hole injection barrier as indicated by the energy gap from CsPbI2Br valance band maximum (VBM) to CuPc highest occupied molecular orbital (HOMO) was estimated to be ~0.26 eV, favoring hole extraction from CsPbI2Br to CuPc, the electron blocking barrier of ~0.04 eV as indicated by the offset between CsPbI2Br conduction band minimum (CBM) and CuPc lowest unoccupied molecular orbital (LUMO) is too small to efficiently block electron transfer. Therefore, the present experimental study implies that CuPc may not be a promising hole transport material for high-performance solar cells using CsPbI2Br as active layer.

scholarly journals Interlayer Engineering of Flexible and Large Area Red Organic Light Emitting Diodes Based on a N-Annulated Perylene Diimide Dimer

2019 ◽  
Author(s):  
Mohammad Rahmati ◽  
Majid Pahlevani ◽  
Gregory Welch
Keyword(s):  
Red Light ◽  
Ambient Air ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Large Area ◽  
Average Roughness ◽  
Light Emitting ◽  
Slot Die

<p>Flexible red OLEDs based on a quadruple layer stack in-between electrodes with 160 mm<sup>2</sup> active area were fabricated in ambient air on PET via slot-die coating. For the OLED structure PET/ITO/PEDOT:PSS/PVK/PFO:tPDI<sub>2</sub>N-EH/ZnO/Ag the ink formulations and coating parameters for each layer were systematically evaluated and optimized. The air-stable red-light emitting material tPDI<sub>2</sub>N-EH was successfully utilized as blended homogeneous film with PFO for the emitting layer. The use of an organic hole-transport layer (PVK) and inorganic electron injection layer (ZnO) significantly improved the brightness of the reference device from 4 cd/m<sup>2</sup> to 303 cd/m<sup>2</sup>. Surface analysis using AFM measurements showed that PVK interlayer reduced the surface roughness of the hole injection layer (PEDT:PSS) from 0.45 nm to 0.17 nm, which improved the ability to form uniform emitting layers on top. In addition, the ZnO interlayer improved the average roughness of the device from 1.26 nm to 0.85 nm and reduced the turn-on voltage of the device from 5.0 V to 2.8 V.</p>

scholarly journals Interlayer Engineering of Flexible and Large Area Red Organic Light Emitting Diodes Based on a N-Annulated Perylene Diimide Dimer

2019 ◽  
Author(s):  
Mohammad Rahmati ◽  
Majid Pahlevani ◽  
Gregory Welch
Keyword(s):  
Red Light ◽  
Ambient Air ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Large Area ◽  
Average Roughness ◽  
Light Emitting ◽  
Slot Die

<p>Flexible red OLEDs based on a quadruple layer stack in-between electrodes with 160 mm<sup>2</sup> active area were fabricated in ambient air on PET via slot-die coating. For the OLED structure PET/ITO/PEDOT:PSS/PVK/PFO:tPDI<sub>2</sub>N-EH/ZnO/Ag the ink formulations and coating parameters for each layer were systematically evaluated and optimized. The air-stable red-light emitting material tPDI<sub>2</sub>N-EH was successfully utilized as blended homogeneous film with PFO for the emitting layer. The use of an organic hole-transport layer (PVK) and inorganic electron injection layer (ZnO) significantly improved the brightness of the reference device from 4 cd/m<sup>2</sup> to 303 cd/m<sup>2</sup>. Surface analysis using AFM measurements showed that PVK interlayer reduced the surface roughness of the hole injection layer (PEDT:PSS) from 0.45 nm to 0.17 nm, which improved the ability to form uniform emitting layers on top. In addition, the ZnO interlayer improved the average roughness of the device from 1.26 nm to 0.85 nm and reduced the turn-on voltage of the device from 5.0 V to 2.8 V.</p>

The Study of Hole Injection in OLEDs with Ultra-Thin Sol-Gel TiO2 Layer

2011 ◽  
Vol 189-193 ◽  
pp. 42-46
Author(s):  
You Wang Hu ◽  
Xiao Yan Sun ◽  
Jian Duan
Keyword(s):  
Sol Gel ◽  
Hole Transport ◽  
Organic Light Emitting Diodes ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Carrier Injection ◽  
Light Emitting ◽  
Organic Light ◽  
Pre Treatment

Organic light-emitting diodes (OLEDs) with inserting an ultrathin sol–gel titanium oxide (TiO2) buffer layer between the ITO anode and hole transport layer (HTL) were fabricated. The carrier injection and the device efficiency were affected by surface morphology of TiO2, which was changed by different plasma pre-treatment of ITO. Treated by CF4 plasma, the TiO2 layer is the smoothest, and treated by H2 plasma it is like island. The TiO2 layer like island is favor of carrier injection from the anode, which was attributed to the point discharged.

scholarly journals Widely applicable phosphomolybdic acid doped poly(9-vinylcarbazole) hole transport layer for perovskite light-emitting devices

RSC Advances ◽  
2019 ◽  
Vol 9 (52) ◽  
pp. 30398-30405
Author(s):  
Yanting Wu ◽  
Zewu Xiao ◽  
Lihong He ◽  
Xiaoli Yang ◽  
Yajun Lian ◽  
...  
Keyword(s):  
Phosphomolybdic Acid ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Wide Range ◽  
Selection Of ◽  
Range Selection

Perovskite light-emitting devices using a PVK:PMA hole transport layer show robust performance, allowing the wide range selection of antisolvents and hole injection layers.

Device optimization of CsSnI2.95F0.05-based all-solid-state dye-sensitized solar cells with non-linear charge-carrier-density dependent photovoltaic behaviors

2015 ◽  
Vol 3 (3) ◽  
pp. 1222-1229 ◽  
Author(s):  
Shuai Ma ◽  
Mingwei Shang ◽  
Liyan Yu ◽  
Lifeng Dong
Keyword(s):  
Solid State ◽  
Dye Sensitized Solar Cells ◽  
Hole Transport ◽  
Hole Injection ◽  
Charge Carrier Density ◽  
Linear Charge ◽  
Dye Sensitized ◽  
Device Optimization ◽  
Non Linear ◽  
Sensitized Solar Cells

Interconnection between hole-transport material and nanoporous electrode is significant for CsSnI2.95F0.05-based all-solid-state DSCs; hole injection determines its non-linear photovoltaic response.

scholarly journals Comparative Study of Printed Multilayer OLED Fabrication through Slot Die Coating, Gravure and Inkjet Printing, and Their Combination

2019 ◽  
Vol 3 (1) ◽  
pp. 32 ◽  
Author(s):  
Lisa Merklein ◽  
Dominik Daume ◽  
Felix Braig ◽  
Stefan Schlisske ◽  
Tobias Rödlmeier ◽  
...  
Keyword(s):  
Inkjet Printing ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Process Window ◽  
Gravure Printing ◽  
Solution Processed ◽  
Slot Die Coating ◽  
Slot Die ◽  
Application Techniques

In this study, multilayer organic light-emitting diodes (OLEDs) consisting of three solution-processed layers are fabricated using slot die coating, gravure printing, and inkjet printing, techniques that are commonly used in the industry. Different technique combinations are investigated to successively deposit a hole injection layer (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS)), a cross-linkable hole transport layer (N,N′-bis(4-(6-((3-ethyloxetan-3-yl)methoxy)-hexyloxy)phenyl)-N,N′-bis(4-methoxyphenyl)biphenyl-4,4′-diamin (QUPD)), and a green emissive layer (TSG-M) on top of each other. In order to compare the application techniques, the ink formulations have to be adapted to the respective process requirements. First, the influence of the application technique on the layer homogeneity of the different materials is investigated. Large area thickness measurements of the layers based on imaging color reflectometry (ICR) are used to compare the application techniques regarding the layer homogeneity and reproducible film thickness. The total stack thickness of all solution-processed layers of 32 OLEDs could be reproduced homogeneously in a process window of 30 nm for the technique combination of slot die coating and inkjet printing. The best efficiency of 13.3 cd A−1 is reached for a process combination of slot die coating and gravure printing. In order to enable a statistically significant evaluation, in total, 96 OLEDs were analyzed and the corresponding 288 layers were measured successively to determine the influence of layer homogeneity on device performance.

scholarly journals Enhanced hole injection assisted by electric dipoles for efficient perovskite light-emitting diodes

2020 ◽  
Vol 1 (1) ◽  
Author(s):  
Xiangtian Xiao ◽  
Kai Wang ◽  
Taikang Ye ◽  
Rui Cai ◽  
Zhenwei Ren ◽  
...  
Keyword(s):  
Electric Dipole ◽  
Light Emitting Diodes ◽  
Hole Transport ◽  
Transport Layer ◽  
Hole Injection ◽  
Hole Transport Layer ◽  
Light Emitting ◽  
Hole Injection Layer ◽  
Dipole Layer ◽  
Electric Dipoles

Abstract Enhanced hole injection is essential to achieve high performance in perovskite light-emitting diodes (LEDs). Here, a strategy is introduced to enhance hole injection by an electric dipole layer. Hopping theory demonstrates electric dipoles between hole injection layer and hole transport layer can enhance hole injection significantly. MoO3 is then chosen as the electric dipole layer between PEDOT:PSS (hole injection layer) and PVK (hole transport layer) to generate electric dipoles due to its deep conduction band level. Theoretical results demonstrate that strong electric fields are produced for efficient hole injection, and recombination rate is substantially increased. Capacitance-voltage analyses further prove efficient hole injection by introducing the electric dipole layer. Based on the proposed electric dipole layer structure, perovskite LEDs achieve a high current efficiency of 72.7 cd A−1, indicating that electric dipole layers are a feasible approach to enhance perovskite LEDs performance.

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