Phenomenology of the Neutral-Ionic Valence Instability in Mixed Stack Charge-Transfer Crystals
Dip. di Scienze Chimiche, della Vita e della Sostenibilità Ambientale and INSTM-UdR di Parma, Parco Area delle Scienze, Università di Parma, I-43124 Parma, Italy
Author to whom correspondence should be addressed.
Received: 15 March 2017 / Revised: 4 April 2017 / Accepted: 6 April 2017 / Published: 11 April 2017
Organic charge-transfer (CT) crystals constitute an important class of functional materials, characterized by the directional charge-transfer interaction between
-electron Donor (D) and Acceptor (A) molecules, with the formation of one-dimensional ...DADAD... stacks. Among the many different and often unique phenomena displayed by this class of crystals, Neutral-Ionic phase transition (NIT) occupies a special place, as it implies a collective
electron transfer along the stack. The analysis of such a complex yet fascinating phenomenon has required many years of investigation, and still presents some open questions and challenges. We present an updated and extensive summary of the phenomenology of the temperature induced NIT, with emphasis on the spectroscopic signatures of the transition. A much shorter summary is given for the NIT induced by pressure. Finally, we report on the exploration, by chemical substitution, of the phase space of ...DADAD... CT crystals, aimed at finding materials with important semiconducting or ferroelectric properties, and at understanding the subtle factors determining the crystal packing.
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MDPI and ACS Style
Masino, M.; Castagnetti, N.; Girlando, A. Phenomenology of the Neutral-Ionic Valence Instability in Mixed Stack Charge-Transfer Crystals. Crystals 2017, 7, 108.
Masino M, Castagnetti N, Girlando A. Phenomenology of the Neutral-Ionic Valence Instability in Mixed Stack Charge-Transfer Crystals. Crystals. 2017; 7(4):108.
Masino, Matteo; Castagnetti, Nicola; Girlando, Alberto. 2017. "Phenomenology of the Neutral-Ionic Valence Instability in Mixed Stack Charge-Transfer Crystals." Crystals 7, no. 4: 108.
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