Effect of Asymmetric External Reorganization Energy on Electron and Hole Transport in Organic Semiconductors

Author(s):  
Tao Xu ◽  
Kangying Cao ◽  
Changwei Wang ◽  
Shiwei Yin

The understanding of the relationship between charge mobilities and the molecular stackings structures of π-conjugated organic semiconducting materials is essential for their development. In this study, the quantum mechanics (QM)-derived...

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3349
Author(s):  
Kyoung-Hwan Kim ◽  
Myung-June Park ◽  
Ju-Hyung Kim

Non-volatile liquid organic semiconducting materials have received much attention as emerging functional materials for organic electronic and optoelectronic devices due to their remarkable advantages. However, charge injection and transport processes are significantly impeded at interfaces between electrodes and liquid organic semiconductors, resulting in overall lower performance compared to conventional solid-state electronic devices. Here we successfully demonstrate efficient charge injection into solvent-free liquid organic semiconductors via cracked metal structures with a large number of edges leading to local electric field enhancement. For this work, thin metal films on deformable polymer substrates were mechanically stretched to generate cracks on the metal surfaces in a controlled manner, and charge injection properties into a typical non-volatile liquid organic semiconducting material, (9-2-ethylhexyl)carbazole (EHCz), were investigated in low bias region (i.e., ohmic current region). It was found that the cracked structures significantly increased the current density at a fixed external bias voltage via the local electric field enhancement, which was strongly supported by field intensity calculation using COMSOL Multiphysics software. We anticipate that these results will significantly contribute to the development and further refinement of various organic electronic and optoelectronic devices based on non-volatile liquid organic semiconducting materials.


2017 ◽  
Vol 8 (21) ◽  
pp. 3286-3293 ◽  
Author(s):  
Bin Mu ◽  
Xingtian Hao ◽  
Jian Chen ◽  
Qian Li ◽  
Chunxiu Zhang ◽  
...  

Well-prepared side-chain discotic liquid crystal polymers with shorter spacers in ordered columnar phases are fascinating and promising cost-effective, solution-processable organic semiconducting materials for various potential optoelectronic device applications.


2021 ◽  
Vol 1744 (3) ◽  
pp. 032176
Author(s):  
Man Zhang ◽  
Yunfei Wu ◽  
Hongyun Cui ◽  
Ju Cheng

2013 ◽  
Vol 46 (19) ◽  
pp. 7705-7714 ◽  
Author(s):  
Zheng Zhao ◽  
Fengjiao Zhang ◽  
Xu Zhang ◽  
Xiaodi Yang ◽  
Hongxiang Li ◽  
...  

2012 ◽  
Vol 13 (12) ◽  
pp. 3244-3253 ◽  
Author(s):  
Gregorio García ◽  
Mónica Moral ◽  
Andrés Garzón ◽  
José M. Granadino-Roldán ◽  
Amparo Navarro ◽  
...  

2007 ◽  
Vol 91 (24) ◽  
pp. 242103 ◽  
Author(s):  
Arne Fleissner ◽  
Hanna Schmid ◽  
Christian Melzer ◽  
Heinz von Seggern

Author(s):  
Jin-Dou Huang ◽  
Jinfeng Zhao ◽  
Kun Yu ◽  
Xiaohua Huang ◽  
Shi-Bo Cheng ◽  
...  

The conducting and optical properties of a series of indeno[1,2-b]fluorene-6,12-dione (IFD)-based molecules have been systematically studied and the influences of butyl, butylthio and dibutylamino substituents on the reorganization energies, intermolecular electronic couplings and charge-injection barriers of IFD have been discussed. The quantum-chemical calculations combined with electron-transfer theory reveal that the incorporation of sulfur-linked side chains decreases reorganization energy associated with hole transfer and optimizes intermolecular π–π stacking, which results in excellent ambipolar charge-transport properties (μh = 1.15 cm2 V−1 s−1 and μe = 0.08 cm2 V−1 s−1); in comparison, addition of dibutylamino side chains increases intermolecular steric interactions and hinders perfect intermolecular π–π stacking, which results in the weak electronic couplings and finally causes the low intrinsic hole mobility (μh = 0.01 cm2 V−1 s−1). Furthermore, electronic spectra of butyl-IFD, butylthio-IFD and dibutylamino-IFD were simulated and compared with the reported experimental data. Calculations demonstrate that IFD-based molecules possess potential for developing novel infrared and near-infrared probe materials via suitable chemical modifications.


2010 ◽  
Vol 15 (1) ◽  
pp. 68 ◽  
Author(s):  
Henry Alberto Méndez-Pinzón ◽  
Diana Rocío Pardo-Pardo ◽  
Juan Pablo Cuéllar-Alvarado ◽  
Juan Carlos Salcedo-Reyes ◽  
Ricardo Vera ◽  
...  

<p>Polymer-based organic light-emitting diodes (OLEDs) with the structure ITO / PEDOT:PSS / MDMO-PPV / Metal were prepared by spin coating. It is known that electroluminescence of these devices is strongly dependent on the material used as cathode and on the deposition parameters of the polymer electroluminescent layer MDMO-PPV. <strong>Objective.</strong> In this work the effect of i) the frequency of the spin coater (1000-8000 rpm), ii) the concentration of the MDMO-PPV: Toluene solution, and iii) the material used as cathode (Aluminium or Silver) on the electrical response of the devices, was evaluated through current-voltage (I-V) measurements. <strong>Materials and methods</strong>. PEDOT:PPS and MDMO-PPV organic layers were deposited by spin coating on ITO substrates, and the OLED structure was completed with cathodes of aluminium and silver. The electric response of the devices was evaluated based on the I-V characteristics. <strong>Results.</strong> Diodes prepared with thinner organic films allow higher currents at lower voltages; this can be achieved either by increasing the frequency of the spin coater or by using concentrations of MDMO-PPV: Toluene lower than 2% weight. A fit of the experimental data showed that the diodes have two contributions to the current. The first one is attributed to parasitic currents between anode and cathode, and the other one is a parallel current through the organic layer, in which the carrier injection mechanism is mediated by thermionic emission. <strong>Conclusions.</strong> The results fitting and the energy level alignment through the whole structure show that PPV-based OLEDs are unipolar devices, with current mainly attributed to hole transport.</p> <p><strong>Key words:</strong> organic semiconductors, OLEDs, electroluminescent polymers, MDMO-PPV, PEDOT:PSS, Spin coating, HOMO, LUMO, carrier injection, thermionic emission.</p><br />


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