Impact of Molecular Organization on Exciton Diffusion in Photosensitive Single-Crystal Halogenated Perylenediimides Charge Transfer Interfaces
authors Pinto, RM; Gouveia, W; Macoas, EMS; Santos, IC; Raja, S; Baleizao, C; Alves, H
nationality International
journal ACS APPLIED MATERIALS & INTERFACES
author keywords organic semiconductors; single crystals; charge-transfer interfaces; photodetectors; perylenediimides
keywords FIELD-EFFECT TRANSISTORS; ORGANIC PHOTOVOLTAIC CELLS; SEMICONDUCTOR THIN-FILMS; SOLAR-CELLS; QUANTUM EFFICIENCY; PERFORMANCE; NANOSTRUCTURES; GENERATION; TRANSPORT; SOLIDS
abstract The efficiency of organic photodetectors and optoelectronic devices is strongly limited by exciton diffusion, in particular for acceptor materials. Although mechanisms for exciton diffusion are well established, their correlation to molecular organization in real systems has received far less attention. In this report, organic single-crystals interfaces were probed with wavelength-dependent photocurrent spectroscopy and their crystal structure resolved using X-ray diffraction. All systems present a dynamic photoresponse, faster than 500 ms, up to 650 nm. A relationship between molecular organization and favorable exciton diffusion in substituted butyl-perylenediimides (PDIB) is established. This is demonstrated by a set of PDIBs with different intra- and interstack distances and short contacts and their impact on photoresponse. Given the short packing distances between PDIs cores along the same stacking direction (3.4-3.7 angstrom), and across parallel stacks (2.5 angstrom), singlet exciton in these PDIBs can follow both Forster and Dexter exciton diffusion, with the Dexter-type mechanism assuming special relevance for interstack exciton diffusion. Yet, the response is maximized in substituted PDIBs, where a 2D percolation network is formed through strong interstack contacts, allowing for PDIBs primary excitons to reach with great efficiency the splitting interface with crystalline rubrene. The importance of short contacts and molecular distances, which is often overlooked as a parameter to consider and optimize when choosing materials for excitonic devices, is emphasized:
publisher AMER CHEMICAL SOC
issn 1944-8244
year published 2015
volume 7
issue 50
beginning page 27720
ending page 27729
digital object identifier (doi) 10.1021/acsami.5b08523
web of science category Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
subject category Science & Technology - Other Topics; Materials Science
unique article identifier WOS:000367561500020
link http://pubs.acs.org/doi/abs/10.1021/acsami.5b08523
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