7 research outputs found
DâAâD-type narrow-bandgap small-molecule photovoltaic donors: pre-synthesis virtual screening using density functional theory
International audienceA new series of DâAâD-type small-molecule photovoltaic donors are designed and virtually screened before synthesis using time-dependent density functional theory calculations carefully validated against various polymeric and molecular donors. In this series of new design, benzodithiophene is kept as D to achieve the optimum highest-occupied molecular orbital energy level, while thienopyrroledione is initially chosen as A but later replaced by difluorinated benzodiathiazole or its selenide derivative to achieve the optimum band gap. The DâAâD core is end-capped by pyridone units which could not only enhance their self-assembly via hydrogen bonds but also play a role as an acceptor (Aâ˛) to form an extended Aâ˛âDâAâDâAⲠsmall-molecule donor
Direct Observation of Confinement Effects of Semiconducting Polymers in Polymer Blend Electronic Systems
Abstract The advent of special types of polymeric semiconductors, known as âpolymer blends,â presents new opportunities for the development of nextâgeneration electronics based on these semiconductors' versatile functionalities in device applications. Although these polymer blends contain semiconducting polymers (SPs) mixed with a considerably high content of insulating polymers, few of these blends unexpectedly yield much higher charge carrier mobilities than those of pure SPs. However, the origin of such an enhancement has remained unclear owing to a lack of cases exhibiting definite improvements in charge carrier mobility, and the limited knowledge concerning the underlying mechanism thereof. In this study, the morphological changes and internal nanostructures of polymer blends based on various SP types with different intermolecular interactions in an insulating polystyrene matrix are investigated. Through this investigation, the physical confinement of donorâacceptor type SP chains in a continuous nanoscale network structure surrounded by polystyrenes is shown to induce structural ordering with more straight edgeâon stacked SP chains. Hereby, highâperformance and transparent organic fieldâeffect transistors with a hole mobility of â5.4 cm2 Vâ1 sâ1 and an average transmittance exceeding 72% in the visible range are achieved
Large-Area Nonfullerene Organic Solar Cell Modules Fabricated by a Temperature-Independent Printing Method
The Role of Long-Alkyl-Group Spacers in Glycolated Copolymers for High-Performance Organic Electrochemical Transistors.
Funder: UK Department for Business, Energy and Industrial StrategyFunder: National Measurement SystemSemiconducting polymers with oligoethylene glycol (OEG) sidechains have attracted strong research interest for organic electrochemical transistor (OECT) applications. However, key molecular design rules for high-performance OECTs via efficient mixed electronic/ionic charge transport are still unclear. In this work, new glycolated copolymers (gDPP-TTT and gDPP-TTVTT) with diketopyrrolopyrrole (DPP) acceptor and thiophene (T) and vinylene (V) thiophene-based donor units are synthesized and characterized for accumulation mode OECTs, where a long-alkyl-group (C12 ) attached to the DPP unit acts as a spacer distancing the OEG groups from the polymer backbone. gDPP-TTVTT shows the highest OECT transconductance (61.9 S cm-1 ) and high operational stability, compared to gDPP-TTT and their alkylated counterparts. Surprisingly, gDPP-TTVTT also shows high electronic charge mobility in a field-effect transistor, suggesting efficient ion injection/diffusion without hindering its efficient electronic charge transport. The elongated donor unit (TTVTT) facilitates hole polaron formation to be more localized to the donor unit, leading to faster and easier polaron formation with less impact on polymer structure during OECT operation, as opposed to the TTT unit. This is supported by molecular dynamics simulation. These simultaneously high electronic and ionic charge-transport properties are achieved due to the long-alkyl-group spacer in amphipathic sidechains, providing an important molecular design rule for glycolated copolymers
In Situ Doping of the PEDOT Top Electrode for All-Solution-Processed Semitransparent Organic Solar Cells
The development of an ideal solution-processable transparent
electrode
has been a challenge in the field of all-solution-processed semitransparent
organic solar cells (ST-OSCs). We present a novel poly(3,4-ethylenedioxythiophene):polystyrenesulfonate
(PEDOT:PSS) top electrode for all-solution-processed ST-OSCs through
in situ doping of PEDOT:PSS. A strongly polarized long perfluoroalkyl
(n = 8) chain-anchored sulfonic acid effectively
eliminates insulating PSS and spontaneously crystallizes PEDOT at
room temperature, leading to outstanding electrical properties and
transparency of PEDOT top electrodes. Doped PEDOT-based ST-OSCs yield
a high power conversion efficiency of 10.9% while providing an average
visible transmittance of 26.0% in the visible range. Moreover, the
strong infrared reflectivity of PEDOT enables ST-OSCs to reject 62.6%
of the heat emitted by sunlight (76.7% from infrared radiation), outperforming
the thermal insulation capability of commercial tint films. This light
management approach using PEDOT enables ST-OSCs to simultaneously
provide energy generation and energy savings, making it the first
discovery toward sustainable energy in buildings