Room-temperature ferroelectricity in supramolecular networks of charge-transfer complexes.
Materials exhibiting a spontaneous electrical polarization that can be switched easily between antiparallel orientations are of potential value for sensors, photonics and energy-efficient memories. In this context, organic ferroelectrics are of particular interest because they promise to be lightweight, inexpensive and easily processed into devices. A recently identified family of organic ferroelectric structures is based on intermolecular charge transfer, where donor and acceptor molecules co-crystallize in an alternating fashion known as a mixed stack: in the crystalline lattice, a collective transfer of electrons from donor to acceptor molecules results in the formation of dipoles that can be realigned by an external field as molecules switch partners in the mixed stack. Although mixed stacks have been investigated extensively, only three systems are known to show ferroelectric switching, all below 71 kelvin. Here we describe supramolecular charge-transfer networks that undergo ferroelectric polarization switching with a ferroelectric Curie temperature above room temperature. These polar and switchable systems utilize a structural synergy between a hydrogen-bonded network and charge-transfer complexation of donor and acceptor molecules in a mixed stack. This supramolecular motif could help guide the development of other functional organic systems that can switch polarization under the influence of electric fields at ambient temperatures.
Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA.
Alok S
AS
Tayi
Alexander K
AK
Shveyd
Andrew C-H
AC
Sue
Jodi M
JM
Szarko
Brian S
BS
Rolczynski
Dennis
D
Cao
T Jackson
TJ
Kennedy
Amy A
AA
Sarjeant
Charlotte L
CL
Stern
Walter F
WF
Paxton
Wei
W
Wu
Sanjeev K
SK
Dey
Albert C
AC
Fahrenbach
Jeffrey R
JR
Guest
Hooman
H
Mohseni
Lin X
LX
Chen
Kang L
KL
Wang
J Fraser
JF
Stoddart
Samuel I
SI
Stupp
D016880:Anisotropy; D003460:Crystallization; D004560:Electricity; D004579:Electron Transport; D004583:Electrons; D006860:Hydrogen Bonding; D007501:Iron / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature
D009942:Organometallic Compounds; D007501:Iron