Jiangzhixiong

Nature Photonics. doi:10.1038/nphoton.2013.276

Authors: Rafael Betancur, Pablo Romero-Gomez, Alberto Martinez-Otero, Xavier Elias, Marc Maymó & Jordi Martorell

Nature Materials. doi:10.1038/nmat3722

Authors: Rodrigo Noriega, Jonathan Rivnay, Koen Vandewal, Felix P. V. Koch, Natalie Stingelin, Paul Smith, Michael F. Toney & Alberto Salleo

Nature Photonics. doi:10.1038/nphoton.2013.188

Authors: Matthew S. White, Martin Kaltenbrunner, Eric D. Głowacki, Kateryna Gutnichenko, Gerald Kettlgruber, Ingrid Graz, Safae Aazou, Christoph Ulbricht, Daniel A. M. Egbe, Matei C. Miron, Zoltan Major, Markus C. Scharber, Tsuyoshi Sekitani, Takao Someya, Siegfried Bauer & Niyazi Serdar Sariciftci

Nature Photonics. doi:10.1038/nphoton.2013.207

Authors: Xugang Guo, Nanjia Zhou, Sylvia J. Lou, Jeremy Smith, Daniel B. Tice, Jonathan W. Hennek, Rocío Ponce Ortiz, Juan T. López Navarrete, Shuyou Li, Joseph Strzalka, Lin X. Chen, Robert P. H. Chang, Antonio Facchetti & Tobin J. Marks

Publication date: October 2013
Source:Organic Electronics, Volume 14, Issue 10
Author(s): M. Slawinski , M. Weingarten , M. Heuken , A. Vescan , H. Kalisch
Luminance homogeneity is an important aspect for large-area (>1cm²) organic light emitting diodes (OLED). Especially, high sheet resistances of transparent contacts lead to a significant brightness inhomogeneity caused by a drop of local potential difference. Therefore the implementation of thin low-resistance metallic grids onto transparent contacts is a crucial development aspect for large-area OLED design. We develop a finite-element electro-optical simulation for OLED using grid structures to optimize geometry, thickness and width of grid elements. We find an exponential relationship between luminance homogeneity and grid material volume, which leads to limitations of minimal grid line width and maximal emissive area for efficient development of large-area OLED.

Graphical abstract

Nano Lett. 2013 Jul 3;
Kyaw AK, Wang DH, Wynands D, Zhang J, Nguyen TQ, Bazan GC, Heeger AJ

We demonstrate that the power conversion efficiency can be significantly improved in solution-processed small-molecule solar cells by tuning the thickness of the active layer and inserting an optical spacer (ZnO) between the active layer and the Al electrode. The enhancement in light absorption in the cell was measured with UV-vis absorption spectroscopy and by measurements of the photoinduced carriers generation rate. The ZnO layer used to improve the light-harvesting increases the charge collection efficiency, serves as a blocking layer for holes, and reduces the recombination rate. The combined optical and electrical improvements raise the power conversion efficiency of solution-processed small-molecule solar cells to 8.9%, that is, comparable to that of polymer counterparts.

Sci Rep. 2013; 3: 1965
Gupta V, Kyaw AK, Wang DH, Chand S, Bazan GC, Heeger AJ

We report Barium (Ba) cathode layer for bulk-heterojunction solar cells which enhanced the fill factor (FF) of p-DTS(FBTTh2)2/PC71BM BHJ solar cell up to 75.1%, one of the highest value reported for an organic solar cell. The external quantum efficiency exceeds 80%. Analysis of recombination mechanisms using the current-voltage (J-V) characteristics at various light intensities in the BHJ solar cell layer reveals that Ba prevents trap assisted Shockley-Read-Hall (SRH) recombination at the interface and with different thicknesses of the Ba, the recombination shifts towards bimolecular from monomolecular. Moreover, Ba increases shunt resistance and decreases the series resistance significantly. This results in an increase in the charge collection probability leading to high FF. This work identifies a new cathode interlayer which outclasses the all the reported interlayers in increasing FF leading to high power conversion efficiency and have significant implications in improving the performance of BHJ solar cells.

Abstract

Abstract

Nature Materials 12, 472 (2013). doi:10.1038/nmat3677

Author: Kosmas Tsakmakidis

Electron-Deficient Poly(p-Phenylene Vinylene) Provides Electron Mobility over 1 cm(2) V(-1) s(-1) under Ambient Conditions.

J Am Chem Soc. 2013 May 15;

Authors: Lei T, Dou JH, Cao XY, Wang JY, Pei J

Abstract
Poly(p-phenylene vinylene) derivatives (PPVs) are one of the most widely investigated p-type polymers in organic electronics. None-theless, PPVs generally exhibit electron mobility lower than 10-4 cm2 V-1 s-1, thus hindering their applications in high-performance polymer FETs and organic photovoltaics. Herein, we design and synthesize a novel electron-deficient PPV derivative, benzodi-furandione-based PPV (BDPPV) which displays high electron mo-bilities up to 1.1 cm2 V-1 s-1 in ambient (4 orders of magnitude higher than other PPVs), because it overcomes common defects in PPVs, such as conformational disorder, weak interchain interaction, and high LUMO level. BDPPV represents the first polymer that can transport electrons over 1 cm2 V-1 s-1 in ambient.

PMID: 23675890 [PubMed - as supplied by publisher]

Nature Photonics. doi:10.1038/nphoton.2013.70

Authors: Benjamin S. Mashford, Matthew Stevenson, Zoran Popovic, Charles Hamilton, Zhaoqun Zhou, Craig Breen, Jonathan Steckel, Vladimir Bulovic, Moungi Bawendi, Seth Coe-Sullivan & Peter T. Kazlas

Nature Materials. doi:10.1038/nmat3622

Authors: Murat Mesta, Marco Carvelli, Rein J. de Vries, Harm van Eersel, Jeroen J. M. van der Holst, Matthias Schober, Mauro Furno, Björn Lüssem, Karl Leo, Peter Loebl, Reinder Coehoorn & Peter A. Bobbert

ACS Appl Mater Interfaces. 2012 Feb; 4(2): 866-70
Subbiah J, Amb CM, Irfan I, Gao Y, Reynolds JR, So F

We have studied the performance of normal and inverted bulk-heterojunction solar cells with an active layer composed of a blend of poly[(4,4'-bis(2-ethylhexyl)dithieno[3,2-b:2',3'-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl] (PDTS-BTD) and {6,6}-phenyl-C71 butyric acid methyl ester (PC(71)BM). For inverted cells, a thin layer of ZnO nanoparticles and MoO(3) were used as interlayers for the bottom cathode and the top anode respectively. To enhance the device performance, a thin film of 4,4',4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (MTDATA) was used along with MoO(3) as an anode interlayer to improve the hole extraction from the photoactive layer to the anode. The inverted polymer solar cells with double interlayer exhibit a higher power conversion efficiency of 6.45% compared to the conventional cell of 4.91% due to efficient charge extraction and favorable vertical morphology of active layer blend. Our ultraviolet photoemission spectroscopy results indicate that the formation of band bending due to interlayer leads to the enhancement in hole extraction.

Adv Mater. 2013 May 7; 25(17): 2397-402
Kyaw AK, Wang DH, Gupta V, Zhang J, Chand S, Bazan GC, Heeger AJ

We successfully demonstrate inverted structure small-molecule (SM) solar cells with an efficiency of 7.88% using ZnO and PEIE as an interfacial layer. Modification of ZnO with a cost-effective PEIE thin layer increases the efficiency of the inverted cell as a result of reducing the work function of the cathode and suppressing the trap-assisted recombination. In addition to the high efficiency, the inverted SM solar cells are relatively stable in air compared to conventional cells.