title: Crystallisation-enhanced bulk hole mobility in phenothiazine-based organic semiconductors.
abstract: A series of three novel donor-acceptor systems based on C(3)-malononitrile-substituted phenothiazines was synthesised in good overall yields and their thermal, spectroscopic, and electrochemical properties were characterised. The compounds were prepared through a sequence of Ullmann-coupling, Vilsmeier-Haack formylation and Knoevenagel-condensation, followed by Suzuki-coupling reactions for introduction of aryl substitutents at C(7) position of the phenothiazine. The introduction of a donor unit at the C(7) position exhibited a weak impact on the optical and electrochemical characteristics of the compounds and led to amorphous films with bulk hole mobilities in the typical range reported for phenothiazines, despite the higher charge delocalisation as attested by computational studies. In contrast, highly ordered films were formed when using the C(7)-unsubstituted 3-malononitrile phenothiazine, exhibiting an outstanding mobility of 1 × 10-3cm2V-1s-1, the highest reported for this class of compounds. Computational conformational analysis of the new phenothizanes suggested that free rotation of the substitutents at the C(7) position suppresses the ordering of the system, thereby hampering suitable packing of the new materials needed for high charge carrier mobility.
authors.affiliation: Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.|Academy of Scientific and Innovative Research, 110025, New Delhi, India.
authors.forename: D B
authors.initials: DB
authors.lastname: Shinde
authors.affiliation: Laboratory of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere, Finland.
authors.forename: Jagadish K
authors.initials: JK
authors.lastname: Salunke
authors.affiliation: Laboratory of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere, Finland.
authors.forename: Nuno R
authors.initials: NR
authors.lastname: Candeias
authors.affiliation: Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, via P. Gobetti 101, I-40129 Bologna, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Tinti
authors.affiliation: Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, via P. Gobetti 101, I-40129 Bologna, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Gazzano
authors.affiliation: Polymer Science and Engineering Division, CSIR-National Chemical Laboratory, Dr Homi Bhabha Road, Pune 411008, India.|Academy of Scientific and Innovative Research, 110025, New Delhi, India.
authors.forename: P P
authors.initials: PP
authors.lastname: Wadgaonkar
authors.affiliation: Laboratory of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere, Finland.
authors.forename: Arri
authors.initials: A
authors.lastname: Priimagi
authors.affiliation: Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, via P. Gobetti 101, I-40129 Bologna, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Camaioni
authors.affiliation: Laboratory of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FI-33101 Tampere, Finland.
authors.forename: Paola
authors.initials: P
authors.lastname: Vivo