Abstract
The effects of replacing the phenyl rings of triphenylamine (TPA) by naphtyl groups are analysed on a series of push-pull molecules containing a 2-thienyl-dicyanovinyl acceptor group. UV-Vis absorption spectroscopy and cyclic voltammetry show that the introduction of one or two naphtyl groups in the structure has limited effects on the optical properties and energy levels of the molecule. On the other hand, the evaluation of the compounds as donor material in bi-layer solar cells with C60 as acceptor shows that the number and mode of linkage of the naphtyl groups exert a marked influence on the power conversion efficiency (PCE) of the cell. Two naphtyl groups lead to a decrease of PCE with respect to TPA, while a single naphtyl group produces opposite effects depending on the linking mode. Compared to TPA, an alpha-naphtyl group leads to a small decrease of PCE while in contrast a beta-naphtyl leads to a ~35% increase of PCE due to improved short-circuit current density (Jsc) and fill-factor. The determination of the hole-mobility of these two donors by the space-charge-limited current method shows that these effects are correlated with the higher hole-mobility of the β-naphtyl compound.
Highlights
Structure-properties relationships in triarylamine-based donor-acceptor molecules containing naphtyl groups as donor material for organic solar cells
The evaluation of the compounds as donor material in bi-layer solar cells with C60 as acceptor shows that the number and mode of linkage of the naphtyl groups exert a marked influence on the power conversion efficiency (PCE) of the cell
Soluble conjugated polymers remain a major class of donor materials for solution-processed bulk heterojunction organic photovoltaics (OPV) cells[1,2,3,4], recent years have seen the emergence of small molecules on the forefront of research on OPV materials owing to the obvious advantages of well-defined chemical structures in terms of reproducibility of synthesis, purification, composition and properties of the materials combined with the possibility to develop more reliable analyses of structure-properties relationships.[5,6,7,8,9]
Summary
Structure-properties relationships in triarylamine-based donor-acceptor molecules containing naphtyl groups as donor material for organic solar cells. Soluble conjugated polymers remain a major class of donor materials for solution-processed bulk heterojunction OPV cells[1,2,3,4], recent years have seen the emergence of small molecules on the forefront of research on OPV materials owing to the obvious advantages of well-defined chemical structures in terms of reproducibility of synthesis, purification, composition and properties of the materials combined with the possibility to develop more reliable analyses of structure-properties relationships.[5,6,7,8,9] After seminal work published in 200510 the design of soluble molecular donors has generated considerable research efforts[5,6,7,8,9,10,11,12,13] and solution-processed bulk heterojunction (BHJ) cells with power conversion efficiency (PCE) of 8.0– 10% have been reported[11,12,13] These results have been obtained with fully optimized solar cells of small active areas and with donor materials of relatively complex chemical structure prepared by multi-step syntheses which can pose the problem of the overall yield, cost environmental impact and scalability of the active material. The synthesis and characterization of the electronic properties of the molecules are described and the effects of the number and mode of linkage of the naphtyl groups on the performances of simple bilayer solar cells with C60 as acceptor material are discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
