posted on 2021-09-10, 13:35authored byHelen Tran, Shayla Nikzad, Jerika A. Chiong, Nathaniel J. Schuster, Amnahir E. Peña-Alcántara, Vivian R. Feig, Yu-Qing Zheng, Zhenan Bao
Featuring
acid-labile yet conjugated bonds along the polymer backbone,
imine-based organic semiconductors are emerging as viable candidates
for transient electronics. To enable their widespread use, a modular
synthesis based on Stille cross-couplings is described herein. Compared
to utilizing imine-based condensation, which is sensitive to interference
from moisture, our approach offers relatively more control over batch-to-batch
reactions. Notably, we show the molecular design and synthesis of
an imine-and-thiophene-containing motif with dibromo or ditin functionality
as building blocks for degradable semiconducting polymers. The building
blocks can be readily copolymerized with aromatic units, which are
commercially available or synthesized from well-established protocols,
conventionally used in semiconducting polymers. In fact, such aromatic
units are likely already available in laboratories synthesizing semiconducting
polymers. In addition to degradable p-type semiconductors, we report
the first degradable n-type semiconducting polymer. The degradable
semiconductors are characterized by nuclear magnetic resonance, gel
permeation chromatography, grazing-incidence X-ray diffraction, and
ultraviolet–visible spectroscopy (UV–vis). The UV–vis
spectra of their solutions and films resemble the spectra of their
nondegradable vinyl analogues; still, we rationalize small differences
between the band gaps with the assistance of density functional theory
and time-dependent density functional theory. The charge carrier mobilities
of the degradable p-type (0.28 cm2/V·s) and n-type
(0.10 cm2/V·s) semiconductors also fare reasonably
well with their nondegradable counterparts. These molecules enabled
the fabrication of inverters, showing expected device characteristics.
Given the ease and efficiency in the synthesis of the imine-containing
building blocks and straightforward preparation of complementary building
blocks for Stille cross-couplings, we anticipate this robust synthetic
scheme to accelerate the exploration of imine-based degradable semiconductors.