Flexible nanogap polymer light-emitting diodes fabricated via adhesion lithography (a-Lith)

We report the development of coplanar green colour organic light-emitting diodes (OLEDs) based on asymmetric nanogap electrodes fabricated on different substrates including glass and plastic. Using adhesion lithography (a-Lith) we pattern Al and Au layers acting as the cathode and anode electrodes, respectively, separated by an inter-electrode distance of <15 nm with an aspect ratio of up to 106. Spin-coating the organic light-emitting polymer poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) on top of the asymmetric Al-Au nanogap electrodes results in green light-emitting nanogap OLEDs with promising operating characteristics. We show that the scaling of the OLED's width from 4 to 200 mm can substantially improve the light output of the device without any adverse effects on the manufacturing yield. Furthermore, it is found that the light-emitting properties in the nanogap area differ from the bulk organic film, an effect attributed to confinement of the conjugated polymer chains in the nanogap channel. These results render a-Lith particularly attractive for low cost facile fabrication of nanoscale light-emitting sources and arrays on different substrates of arbitrary size

Fabrication of air-stable, large-area, PCDTBT:PC70BM polymer solar cell modules using a custom built slot-die coater Solar Energy Materials and Solar Cells

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Precise Characterisation of Molecular Orientation in a Single Crystal Field-Effect Transistor Using Polarised Raman Spectroscopy

Charge transport in organic semiconductors is strongly dependent on the molecular orientation and packing, such that manipulation of this molecular packing is a proven technique for enhancing the charge mobility in organic transistors. However, quantitative measurements of molecular orientation in micrometre-scale structures are experimentally challenging. Several research groups have suggested polarised Raman spectroscopy as a suitable technique for these measurements and have been able to partially characterise molecular orientations using one or two orientation parameters. Here we demonstrate a new approach that allows quantitative measurements of molecular orientations in terms of three parameters, offering the complete characterisation of a three-dimensional orientation. We apply this new method to organic semiconductor molecules in a single crystal field-effect transistor in order to correlate the measured orientation with charge carrier mobility measurements. This approach offers the opportunity for micrometre resolution (diffraction limited) spatial mapping of molecular orientation using bench-top apparatus, enabling a rational approach towards controlling this orientation to achieve optimum device performance.This work was funded by the Department for Business, Innovation & Skills through the National Measurement System as part of the Innovation, Research and Development programme. M.S. acknowledges equipment funding from EPSRC UK Grant EP/I017569/1. S.G. and M.T would like to acknowledge the financial support from ERC StG 2012-306826 e-GAMES project and CIBER-BBN. Thanks are due to Prof. J.E. Anthony and his group from the University of Kentucky, for synthesising the functionalised pentacene derivative used in this work, and also, to J. Wade at Imperial College London for the DFT calculations.Peer reviewe

Dataset on the absorption of PCDTBT:PC70BM layers and the electro-optical characteristics of air-stable, large-area PCDTBT:PC70BM-based polymer solar cell modules, deposited with a custom built slot-die coater

The data presented in this article is related to the research article entitled “Fabrication of air-stable, large-area, PCDTBT:PC70BM polymer solar cell modules using a custom built slot-die coater” (D.I. Kutsarov, E. New, F. Bausi, A. Zoladek-Lemanczyk, F.A. Castro, S.R.P. Silva, 2016) [1]. The repository name and reference number for the raw data from the abovementioned publication can be found under: https://doi.org/10.15126/surreydata.00813106. In this data in brief article, additional information about the absorption properties of PCDTBT:PC70BM layers deposited from a 12.5 mg/ml and 15 mg/ml photoactive layer dispersion are shown. Additionally, the best and average J-V curves of single cells, fabricated from the 10 and 15 mg/ml dispersions, are presented

Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

The authors acknowledge funding from the Technology Strategy Board (TSB) SCALLOPS project, UK. NK, AZL, DR, and FAC acknowledge funding from the UK Department of Business Innovation and Skills, through the National Measurement System. JN acknowledges the support of the Engineering and Physical Sciences Research Council via grants EP/K030671/1, EP/K029843/1 and the Supersolar Energy Hub (EP/J017361/1), and The Royal Society via a Wolfson Merit Award

Photochemical Transformations in Fullerene and Molybdenum Oxide Affect the Stability of Bilayer Organic Solar Cells

Thin films of fullerene C-60 and molybdenum oxide (MoO3) are ubiquitously used as the electron acceptor material and hole extraction interfacial layer for the fabrication of organic photovoltaic (OPV) cells. It is well known that light exposure induces color changes in MoO3 (photochromism) and the formation of intermolecular bonds between C-60 molecules (photopolymerization). The influence of these photoinduced reactions on the long-term stability of OPV cells, however, has not previously been studied in detail. Here, a study and discussion of the early (<5 days) aging mechanisms occurring in illuminated ITO/MoO3/organic cyanine dye/C-60/Alq(3)/Ag bilayer solar cells under nitrogen atmosphere is presented. A degradation process at the organic heterojunction is identified and the formation of Mo5+ species during illumination is found to adversely affect cell behavior. For these widely used materials, the results suggest that light processing is a first necessary step before OPV characteristics can be meaningfully rated

Simultaneous topographical, electrical and optical microscopy of optoelectronic devices at the nanoscale

The authors acknowledge funding from the Technology Strategy Board (TSB) SCALLOPS project, UK. NK, AZL, DR, and FAC acknowledge funding from the UK Department of Business Innovation and Skills, through the National Measurement System. JN acknowledges the support of the Engineering and Physical Sciences Research Council via grants EP/K030671/1, EP/K029843/1 and the Supersolar Energy Hub (EP/J017361/1), and The Royal Society via a Wolfson Merit Award