TY - JOUR
T1 - Twisted tetrathiafulvalene crystals
AU - Yang, Yongfan
AU - Zong, Kai
AU - Whittaker, St John
AU - An, Zhihua
AU - Tan, Melissa
AU - Zhou, Hengyu
AU - Shtukenberg, Alexander G.
AU - Kahr, Bart
AU - Lee, Stephanie S.
N1 - Funding Information:
This work was primarily supported by the National Science Foundation DMR-2003997 and secondarily by the New York University Materials Research Science and Engineering Center (MRSEC) program of the National Science Foundation under award number DMR-1420073. The X-ray microdiffractometer with GADDS was acquired through the support of the National Science Foundation under Award Number CRIF/CHE-0840277 and NSF MRSEC Program under Award Number DMR-0820341. The authors also acknowledge support from PSEG to advance energy innovation at Stevens Institute of Technology. The authors thank Dr. Chunhua (Tony) Hu for assistance with X-ray diffraction experiments, Dr. Detlef.-M. Smilgies for assistance with indexGIXS, and Dr. Camille Farfan for graphic design support.
Publisher Copyright:
© 2022 The Royal Society of Chemistry.
PY - 2022/2/16
Y1 - 2022/2/16
N2 - Optically-active optoelectronic materials are of great interest for many applications, including chiral sensing and circularly polarized light emission. Traditionally, such applications have been enabled by synthetic strategies to design chiral organic semiconductors and conductors. Here, centrosymmetric tetrathiafulvalene (TTF) crystals are rendered chiral on the mesoscale by crystal twisting. During crystallization from the melt, helicoidal TTF fibers were observed to grow radially outwards from a nucleation centre as spherulites, twisting in concert about the growth direction. Because molecular crystals exhibit orientation-dependent refractive indices, periodic concentric bands associated with continually rotating crystal orientations were observed within the spherulites when imaged between crossed polarizers. Under certain conditions, concomitant crystal twisting and bending was observed, resulting in anomolous crystal optical behavior. X-ray diffraction measurements collected on different spherulite bands indicated no difference in the molecular packing between straight and twisted TTF crystals, as expected for microscopic twisting pitches between 20-200 μm. Mueller matrix imaging, however, revealed preferential absorption and refraction of left- or right-circularly polarized light in twisted crystals depending on the twist sense, either clockwise or counterclockwise, about the growth direction. Furthermore, hole mobilities of 2.0 ± 0.9 × 10−6 cm2 V−1 s−1 and 1.9 ± 0.8 × 10−5 cm2 V−1 s−1 were measured for straight and twisted TTF crystals deposited on organic field-effect transistor platforms, respectively, demonstrating that crystal twisting does not negatively impact charge transport in these systems.
AB - Optically-active optoelectronic materials are of great interest for many applications, including chiral sensing and circularly polarized light emission. Traditionally, such applications have been enabled by synthetic strategies to design chiral organic semiconductors and conductors. Here, centrosymmetric tetrathiafulvalene (TTF) crystals are rendered chiral on the mesoscale by crystal twisting. During crystallization from the melt, helicoidal TTF fibers were observed to grow radially outwards from a nucleation centre as spherulites, twisting in concert about the growth direction. Because molecular crystals exhibit orientation-dependent refractive indices, periodic concentric bands associated with continually rotating crystal orientations were observed within the spherulites when imaged between crossed polarizers. Under certain conditions, concomitant crystal twisting and bending was observed, resulting in anomolous crystal optical behavior. X-ray diffraction measurements collected on different spherulite bands indicated no difference in the molecular packing between straight and twisted TTF crystals, as expected for microscopic twisting pitches between 20-200 μm. Mueller matrix imaging, however, revealed preferential absorption and refraction of left- or right-circularly polarized light in twisted crystals depending on the twist sense, either clockwise or counterclockwise, about the growth direction. Furthermore, hole mobilities of 2.0 ± 0.9 × 10−6 cm2 V−1 s−1 and 1.9 ± 0.8 × 10−5 cm2 V−1 s−1 were measured for straight and twisted TTF crystals deposited on organic field-effect transistor platforms, respectively, demonstrating that crystal twisting does not negatively impact charge transport in these systems.
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U2 - 10.1039/d2me00010e
DO - 10.1039/d2me00010e
M3 - Article
AN - SCOPUS:85133160258
SN - 2058-9689
VL - 7
SP - 569
EP - 576
JO - Molecular Systems Design and Engineering
JF - Molecular Systems Design and Engineering
IS - 6
ER -