Achieving efficient bulk‐heterojunction (BHJ) solar cells from blends of solution‐processable small‐molecule (SM) donors and acceptors is proved particularly challenging due to the complexity in ...obtaining a favorable donor–acceptor morphology. In this report, the BHJ device performance pattern of a set of analogous, well‐defined SM donors—DR3TBDTT (DR3), SMPV1, and BTR—used in conjunction with the SM acceptor IDTTBM is examined. Examinations show that the nonfullerene “All‐SM” BHJ solar cells made with DR3 and IDTTBM can achieve power conversion efficiencies (PCEs) of up to ≈4.5% (avg. 4.0%) when the solution‐processing additive 1,8‐diiodooctane (DIO, 0.8% v/v) is used in the blend solutions. The figures of merit of optimized DR3:IDTTBM solar cells contrast with those of “as‐cast” BHJ devices from which only modest PCEs <1% can be achieved. Combining electron energy loss spectrum analyses in scanning transmission electron microscopy mode, carrier transport measurements via “metal‐insulator‐semiconductor carrier extraction” methods, and systematic recombination examinations by light‐dependence and transient photocurrent analyses, it is shown that DIO plays a determining role—establishing a favorable lengthscale for the phase‐separated SM donor–acceptor network and, in turn, improving the balance in hole/electron mobilities and the carrier collection efficiencies overall.
A set of structurally analogous small‐molecule (SM) donors with distinct side‐chain manifolds shows significant differences in their performance patterns in bulk‐heterojunction (BHJ) devices with the nonfullerene SM acceptor IDTTBM. Reducing the lengthscale of the phase‐separated network between donor and acceptor effectively suppresses nongeminate recombination in the BHJ active layers and improves the carrier mobility balance.
Vulvodynia is a condition characterised by persistent vulval pain and includes particular impacts on sexual and emotional functioning. Acceptance and Commitment Therapy (ACT) has been successfully ...applied in persistent pain but has not been tested in this population. This single-case experimental design (SCED) study aimed to evaluate whether an online ACT programme improves clinical outcomes in women with Vulvodynia. We also evaluated whether the intervention led to changes in hypothesised processes of therapeutic change.
This study applied a nonconcurrent multiple baseline SCED method to assess ACT in women with Vulvodynia. During baseline and treatment phases, participants completed daily self-report outcomes of pain severity and interference, sexual functioning and satisfaction, depression, and hypothesised process-variables: pain-acceptance, present-moment-awareness, committed-action, perceived injustice, and body-exposure anxiety during sexual activities. Full-length assessments of these variables were also completed before and after treatment. The intervention comprised a six-week online ACT programme, combined with a Vulvodynia-specific manual. Visual and statistical analyses were conducted.
Seven participants, mostly with mixed Vulvodynia, provided baseline and treatment phase data, and completed the intervention and diaries. Based on the visual inspection, and Tau and Tau-U values as effect sizes from the daily data, all participants showed moderate size improvements in two or more outcomes. However, participants had highly individual treatment effects. Limited improvement was found in depression. Pain-acceptance, committed-action, and perceived injustice also demonstrated change for some participants.
The results suggest online ACT may improve pain and sexual outcomes for some women with Vulvodynia. Pain-acceptance, committed-action, and perceived injustice are highlighted as potential processes of change for some participants. In general, responses to treatment appear highly individual. Further application of the SCED approach to ACT for Vulvodynia is recommended.
•Vulvodynia involves persistent vulval pain, sexual impacts, and depression.•Acceptance and Commitment therapy (ACT) has not been tested in Vulvodynia.•Online ACT was tested using a single-case experimental design (SCED) in 7 women.•Pain, sexual outcomes, and processes of change improved in most women following ACT.•This SCED study suggests ACT represents a promising avenue in this population.
The connectivity between ordered domains in semiconducting polymers has been implicated as a bottleneck to charge transport. Crystallites in stiff-chain polymers have been shown to have ordered ...quasi-epitaxial domain boundaries using electron microscopy, but the factors affecting their formation have not been elucidated. A series of poly(benzo1,2-b:4,5-b′dithiophene–thieno3,4-cpyrrole-4,6-dione) (PBDTTPD) polymers with varying side chains were studied to determine the role of molecular structure on the formation of domain boundaries. Grazing incidence wide-angle X-ray scattering revealed the texture of ordered domains in these polymers as a function of thickness and thermal processing. High-resolution transmission electron microscopy (HRTEM) of thin films revealed that crystallites overlapped in an ordered fashion based on a geometric rule for the length of the crystallographic repeat length and the separation of the backbone by the side chains. All of the PBDTTPD polymers had polymorphic crystallites due to differences in alkyl stacking that behaved differently depending on their orientation to the substrate during thermal annealing. These results show the importance of domain orientation and boundaries on the morphology of semiconducting polymers.
All-organic infrared (IR)-to-visible upconversion organic light-emitting diodes (OLEDs) with an IR sensitivity up to 1100 nm were fabricated using a low-band-gap polymer as the organic IR sensitizing ...layer. A novel low-band-gap (1 eV) polymer, poly 4-(4,8-bis(5-(2-butyloctyl)thiophen-2-yl)benzo1,2-b:4,5-b′dithiophen-2-yl)-6,7-diethyl-1,2,5 thiadiazolo3,4-gquinoxaline (PBDTT-BTQ), with a strong photoresponse in near-IR wavelengths of 700–1100 nm was first synthesized using a thiadiazolo3,4quinoxaline (BTQ) and a thiophene-substituted benzo1,2-b:4,5-b2-bdithiophene (BDTT) as the electron-withdrawing and donating building blocks, respectively. The near-IR photodetector was then fabricated for evaluating a PBDTT-BTQ as the IR sensitizing layer. The PBDTT-BTQ IR photodetector showed detectivity greater than 1011 Jones in the multispectral region (300–1100 nm) and the maximum detectivity of 3.1× 1011 Jones at the wavelength of 1000 nm due to significantly reducing dark current (8.8 × 10–6 mA/cm2 at −1 V). Finally, the all-organic IR upconversion OLED with a PBDTT-BTQ IR sensitizer successfully converted invisible near-IR light of 700–1100 nm directly to visible green light with a peak emission wavelength of 520 nm. This is the first report of an all-organic IR-to-visible upconversion OLED with near-IR sensitivity up to 1100 nm.
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•Synthesis of conjugated polymers under mild conditions.•Controlled alkyne polyaddition process with a commercial catalyst.•High trans-stereoselectivity of the arylenyne repeating ...units.•Side chain alkyl branching and luminescence properties.•Processability and aggregation conditions of PPEV polymers;
Novel poly(p-phenyleneethynylenevinylene)s (PPEV) have been synthesized by step-growth oligomerization of 2,5-diethynyl-1,4-dialkoxybenzene monomers promoted by the ruthenium pre-catalyst {RuCl(μ-Cl)(η6-p-cymene)}2 in the solvent mixture AcOH/CH2Cl2. The presence of the branched side chains 2-ethylhexyloxy or 3,7-dimethyloctyloxy in the phenylene unit allows for the formation of soluble π-conjugated short polymers, with slightly increased degree of polymerization (Xn = 5 - 10) and red-shifted photophysical properties (λem ≅ 515 nm in CHCl3) with respect to the analogues with linear alkoxy side chains. The aggregation properties of the polymer with 2-ethylhexyloxy groups have been investigated by an osmosis driven procedure, yielding nanospheres of different size depending on the adapted solvent/nonsolvent mixture.
Non-fullerene acceptor (NFA)-based organic solar cells have outperformed fullerene-based devices, yet their photophysics is less well understood. Herein, changes in the donor polymer backbone ...sidechain substitution and backbone fluorination in benzodithiophene–thiophene copolymers are linked to the photophysical processes and performance of bulk heterojunction (BHJ) solar cells using ITIC as the NFA. Increased geminate recombination is observed when the donor polymer is alkoxy-substituted in conjunction with faster nongeminate recombination of free charges, limiting both the short-circuit current and device fill factor (FF). In contrast, thienyl-substitution reduces geminate recombination, albeit nongeminate recombination remains significant, leading to improved short-circuit current density, yet not the FF. Only the combination of thienyl-substitution and polymer backbone fluorination yields both efficient charge separation and significantly reduced nongeminate recombination, resulting in FFs in excess of 60%. Time-delayed collection field measurements ascertain that charge generation is field independent in the thienyl-substituted donor polymer:ITIC systems, whereas weakly field dependent in the alkoxy-substituted polymer:ITIC blend, indicating that the low FFs are primarily caused by nongeminate recombination. This work provides insight into the interplay of donor polymer structure, BHJ photophysics, and device performance for a prototypical NFA, namely, ITIC. More specifically, it links the donor polymer chemical structure to quantifiable changes of kinetic parameters and the yield of individual processes in ITIC-based BHJ blends.
Polymer acceptors are a class of “non‐fullerene” electron‐transporting materials that can replace 6,6‐phenyl C61/71 butyric acid (PC61/71BM) in bulk‐heterojunction (BHJ) solar cells. In this ...contribution is reported the use of N‐acyl‐substituted isoindigo (IID) motifs (IID(CO)) as electron‐deficient units in the design of polymer acceptors for “all‐polymer” BHJ solar cells. While IID motifs are commonly used in the design of polymer donors for efficient BHJ solar cells with the fullerene PC61/71BM acceptors, here it is shown that IID(CO) building units used in conjunction with suitable co‐monomers represent a practical avenue for polymer acceptors with electron affinity values comparable to that of PC61/71BM (i.e., 4.2 eV).
N‐acyl‐substituted IID motifs (IID(CO)) as electron‐deficient units in the design of polymer acceptors for “all‐polymer” BHJ solar cells are presented. IID(CO) building units used in conjunction with suitable co‐monomers represent a practical avenue for polymer acceptors with electron affinity values comparable to that of 6,6‐phenyl C61/71 butyric acid (i.e., 4.2 eV).
Two-step synthesis of EDOT (3,4-ethylenedioxythiophene) derivate bearing a carboxylic acid group (carboxyl-EDOT) is presented. This reactive monomer has been copolymerized with EDOT to afford PEDOT ...copolymers. Thanks to the most common additives usually added to the PEDOT:PSS dispersion, ethylene glycol and 4-dodecylbenzenesulfonic acid (DBSA), the carboxylic acid has been used to cross-link the material via esterification reactions. This result offers the possibility to produce a polymer network without adding any cross-linking agent. Furthermore, the short synthetic pathway of carboxyl-EDOT offers the possibility to incorporate new functionality either in EDOT monomer or in PEDOT materials with a reasonable chemical effort and background.
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