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Poly-3-hexylthiophene (P3HT) is a benchmark semiconducting polymer in organic electronics. Ion-gated transistors (IGTs), making use of ionic gating media, are particularly interesting for flexible and printable␣organic electronic applications. The molecular weight of P3HT is known to affect the morphology and structure of the corresponding films and, ultimately, the performance of devices based thereon. Here we report on IGTs based on films of P3HT with different molecular weights (∼ 20 kDa, 30–50 kDa and 80–90 kDa) and, as the gating medium, the well-investigated ionic liquid [EMIM][TFSI], to investigate the effects of the film morphological and structural properties on charge carrier transport and, eventually, IGT performance. P3HT films were deposited over rigid (SiO2/Si) and flexible (polyimide) substrates. All the P3HT IGTs could be operated at low voltage (about 1 V) and achieved a hole mobility larger than 0.1 cm2 V−1 s−1, pointing to the extremely favorable [EMIM][TFSI]/P3HT interface for IGT applications, for all the molecular weights investigated. We finally investigated the stability of flexible devices considering two different bending radii (R = 10 mm and R = 5 mm). [ABSTRACT FROM AUTHOR]

In bulk heterojunction (BHJ) polymeric organic solar cells (OSCs), the use of processing additives in the material formulation has emerged as a promising, cost-effective, and widely applicable method for optimizing the phase separation between the donor (D) and acceptor (A) materials, thus increasing their efficiency. So far, however, there has been no systematic approach for identifying suitable processing additives for a given D:A system. A method based on the Hansen solubility parameters (HSPs) is proposed for guiding the selection of processing additives for a given D:A combination. The method is applied to the archetypical poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) system. The HSPs of these materials are determined and used to define a set of numerical criteria that need to be satisfied by a processing additive in order for it to be effective in realizing a higher efficiency OSC. Applying the selection criteria results in the identification of three novel processing additives. OSCs made of these formulations demonstrate an increase in their short-circuit current density ( JSC) and power conversion efficiency (PCE). These results demonstrate the efficiency of these novel processing additives and show that the HSPs represent a useful tool to determine and explore new types of processing additives for BHJ-OSCs. [ABSTRACT FROM AUTHOR]

Organic materials and blends have received a great deal of interests for application in large area, flexible, and low-cost organic/hybrid electronics. In this work the optical, structural and the electrical behaviors of a new active layer system composed by functionalized gold nanoparticles (AuNPs) and conjugated polymers, were investigated. For this purpose, gold nanoparticles with diameter of about 5 nm were chosen, coated with the bifunctional π-conjugated ligand (9,9-didodecyl-2,7-bis(acetylthio)fluorene, FL) for their high stability and easy dispersibility in organic solvents. The blends based on AuNPs and regioregular poly-3-hexylthiophene (P3HT) were prepared by adding an increasing percentage by weight of nanoparticles, i.e. from 10% to 90 wt%, in the P3HT polymeric matrix. The presence of nanoparticles was confirmed by UV-Vis spectroscopy, electron microscopy and X-ray diffraction techniques. The optical characterization of the composites demonstrated the possibility to tune the optical behavior of the P3HT by adding increasing percentages of AuNPs into the polymer matrix. Their inclusion results in a loss of P3HT crystallinity and in a simultaneous increase of the π-π interaction between the polythiophene chain and fluorene ligand. To better investigate the films, Grazing Incident X-ray Diffraction (GIXD) measurements were carried out and the blend containing 30 wt% of AuNPs in P3HT reveals an optimal condition, combining good structural order and interconnectivity in the polymer matrix. The electrical characterization of the AuNPs/P3HT blends reveals an improvement of the electrical conductivity in all the prepared blends, that show higher conductivity values compared to the pristine AuNPs and P3HT materials. The best performance is achieved adding 30 wt% of AuNPs to P3HT resulting in an enhancement of conductivity by about 350% compared to that of the pure polymer. This result could be of great interest for the realization of new conductive film composites to use in opto-electronic devices. [Display omitted] • Gold nanoparticles (AuNPs) and regioregular poly-3-hexylthiophene (P3HT) were blended in different weight percentages. • Tuning of the structural and optical features by increasing percentages of AuNPs into the P3HT matrix. • The electrical characterization of the AuNPs/P3HT blends reveals a substantial improvement of the conductivity. • The best performance is achieved adding 30%wt of AuNPs to P3HT with 350% enhancement of conductivity compared to pure P3HT. [ABSTRACT FROM AUTHOR]

In this brief, various approaches for the realization of transparent photodiodes based on bulk heterojunction blends of poly-3-hexylthiophene and [6,6]-phenyl C61-butyric acid methyl ester are studied. The choice of the constituents of the device is discussed concerning transmittance and light-detecting properties as dark current and external quantum efficiency (EQE). Blending several light-absorbing materials makes tailoring of the transmittance spectrum possible. Transmittance of 36% of the incident light together with 46% EQE at a wavelength of 530 nm are promising results and show the potential for highly transparent photodiodes based on organic layers. [ABSTRACT FROM AUTHOR]

Electric field stimulation is known to affect various cellular processes, including cell fate specification and differentiation, particularly towards neuronal lineages. This makes it a promising therapeutic strategy to stimulate regeneration of neuronal tissues. Retinal ganglion cells (RGCs) is a type of neural cells of the retina responsible for transduction of visual signals from the retina to the brain cortex, and is often degenerated in various blindness-causing retinal diseases. The organic photovoltaic materials such as poly-3-hexylthiophene (P3HT) can generate electric current upon illumination with light of the visible spectrum, and possesses several advantageous properties, including light weight, flexibility and high biocompatibility, which makes them a highly promising tool for electric stimulation of cells in vitro and in vivo. In this study, we tested the ability to generate photocurrent by several formulations of blend (bulk heterojunction) of P3HT (which is electron donor material) with several electron acceptor materials, including Alq3 and bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq2). We found that the photovoltaic device based on bulk heterojunction of P3HT with Bebq2 could generate photocurrent when illuminated by both green laser and visible spectrum light. We tested the growth and differentiation capacity of human induced pluripotent stem cells (hiPSC)-derived RGCs when grown in interface with such photostimulated device, and found that they were significantly increased. The application of P3HT:Bebq2-formulation of photovoltaic device has a great potential for developments in retinal transplantation, nerve repair and tissue engineering approaches of treatment of retinal degeneration. [ABSTRACT FROM AUTHOR]