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bandgap donor–acceptor organic semiconductors are
generally considered to show a closed-shell singlet ground state,
and their radicals are reported as impurities, defects, polarons,
and charge transfer monoradicals. Herein, we systematically investigated
the open-shell singlet diradical electronic ground state of two diketopyrrolopyrrole-based
compounds via the combination of electron spin resonance (ESR), nuclear
magnetic resonance, superconducting quantum interference device magnetometry,
and theoretical calculations. It is widely known that the quinoidal
character will be significantly enhanced in the aggregation state
accompanied by improved planarity and enhanced delocalization. We
proposed an aggregation-induced radical and captodative effect as
the driving force for the formation and stabilization of the open-shell
quinoid diradical based on the ESR test in different proportions of
mixed solvents. Our results provided a novel view for understanding
the intrinsic chemical structure of donor–acceptor organic
semiconductors, the open-shell singlet and thermally excited triplet
electronic states, and the unexpected physical processes between the
ground state and the excited state.
It is very challenging to prepare stable radicals as they are usually thermodynamically or kinetically unstable in air. Herein, a series of star‐shaped aromatic nitric acid radicals were prepared via facile demethylation and consequent oxidation. As phenol radicals without steric hindrance group protection, they exhibit high electrochemical and thermal stability due to their rich resonance structures including closed‐shell nitro‐like and open‐shell nitroxide structure with unpaired electrons delocalized in conjugated backbones. Among them, TPA‐TPA‐O6 powder exhibited extremely wide absorption from 300 to 2000 nm covering the whole solar spectral irradiance, high photothermal conversion efficiency, and negligible photobleaching effect in seawater desalination. Under the irradiation of one sunlight, the water evaporation efficiency of TPA‐TPA‐O6 is recorded to be as high as 89.41 % and the water evaporation rate is 1.293 kg m−2 h−1, which represents the top performance in pure organic small molecule photothermal materials.
Among the various conducting polymers, polyaniline (PANI) has received a great deal of attention due to its low cost, excellent chemical and thermal stabilities, and high electrical conductivity. Herein, a newly designed self‐doped water‐soluble PANI derivatives‐poly (diphenylamine‐4‐sulfonic acid) (PDAS) is readily prepared and applied as hole extract layer in nonfullerene organic solar cells. PDAS, with satisfactory structural and electrical homogeneity, exhibits high conductivity of 7.75 × 10−2 S cm−1, none of acidity (with pH around 7), as well as enhanced work function of 5.43 eV, compared with the well‐known poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS). The power conversion efficiency of PDAS‐based devices is comparable with that of PEDOT:PSS‐based devices with the PM6:BTP‐4F‐12 as active layer. The successful design of the new self‐doped water‐soluble conductive polymer and its commercial application potential is demonstrated.
The development of tin (Sn)-based perovskite solar cells has attracted extensive attention due to its strong infrared absorption and non-toxicity properties. However, the self-doping effect of Sn2+ oxidation leads to...
It is very challenging to prepare stable radicals as they are usually thermodynamically or kinetically unstable in air. Herein, a series of star-shaped aromatic nitric acid radicals were prepared via facile demethylation and consequent oxidation. As phenol radicals without steric hindrance group protection, they exhibit high electrochemical and thermal stability due to their rich resonance structures including closed-shell nitro-like and open-shell nitroxide structure with unpaired electrons delocalized in conjugated backbones. Among them, TPA-TPA-O 6 powder exhibited extremely wide absorption from 300 to 2000 nm covering the whole solar spectral irradiance, high photothermal conversion efficiency, and negligible photobleaching effect in seawater desalination. Under the irradiation of one sunlight, the water evaporation efficiency of TPA-TPA-O 6 is recorded to be as high as 89.41 % and the water evaporation rate is 1.293 kg m À 2 h À 1 , which represents the top performance in pure organic small molecule photothermal materials.
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