Macroscopic Domains within an Oriented TQ1 Film Visualized Using 2D Polarization Imaging

Large-area self-assembly of functional conjugated polymers holds a great potential for practical applications of organic electronic devices. We obtained well-aligned films of poly­[2,3-bis­(3-octyloxyphenyl)­quinoxaline-5,8-diyl-<i>alt</i>-thiophene-2,5-diyl] (TQ1) using the floating film transfer method. Thereby, a droplet of the TQ1 solution was injected on top of the surface of an immiscible liquid substrate, at the meniscus formed at the edge of a Petri dish, from where the polymer solution and the film spread in one direction. Characterization of the TQ1 film using the recently developed two-dimensional polarization imaging (2D POLIM) revealed large, millimeter-sized domains of oriented polymer chains. The irregular shape of the contact line at the droplet source induced the appearance of disordered stripes perpendicular to the spreading direction. A correlation of polarization parameters measured using 2D POLIM revealed the microstructure of such stripes, providing valuable information for further improvement and possible upscaling of this promising method

Macroscopic Domains within an Oriented TQ1 Film Visualized Using 2D Polarization Imaging

Large-area self-assembly of functional conjugated polymers holds a great potential for practical applications of organic electronic devices. We obtained well-aligned films of poly­[2,3-bis­(3-octyloxyphenyl)­quinoxaline-5,8-diyl-<i>alt</i>-thiophene-2,5-diyl] (TQ1) using the floating film transfer method. Thereby, a droplet of the TQ1 solution was injected on top of the surface of an immiscible liquid substrate, at the meniscus formed at the edge of a Petri dish, from where the polymer solution and the film spread in one direction. Characterization of the TQ1 film using the recently developed two-dimensional polarization imaging (2D POLIM) revealed large, millimeter-sized domains of oriented polymer chains. The irregular shape of the contact line at the droplet source induced the appearance of disordered stripes perpendicular to the spreading direction. A correlation of polarization parameters measured using 2D POLIM revealed the microstructure of such stripes, providing valuable information for further improvement and possible upscaling of this promising method

DNA Based Hybrid Material for Interface Engineering in Polymer Solar Cells

A new solution processable electron transport material (ETM) is introduced for use in photovoltaic devices, which consists of a metallic conjugated polyelectrolyte, poly­(4-(2,3-dihydrothieno­[3,4-<i>b</i>]­[1,4]­dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S), and surfactant-functionalized deoxyribonucleic acid (DNA) (named DNA:CTMA:PEDOT-S). This ETM is demonstrated to effectively work for bulk-heterojunction organic photovoltaic devices (OPV) based on different electron acceptor materials. The fill factor, the open circuit voltage, and the overall power conversion efficiency of the solar cells with a DNA:CTMA:PEDOT-S modified cathode are comparable to those of devices with a traditional lithium fluoride/aluminum cathode. The new electron transport layer has high optical transmittance, desired work function and selective electron transport. A dipole effect induced by the use of the surfactant cetyltrimethylammonium chloride (CTMA) is responsible for lowering the electrode work function. The DNA:CTMA complex works as an optical absorption dilutor, while PEDOT-S provides the conducting pathway for electron transport, and allows thicker layer to be used, enabling printing. This materials design opens a new pathway to harness and optimize the electronic and optical properties of printable interface materials

Additional file 2: Table S2. of Molecular detection of Porcine astrovirus in Sichuan Province, China

Characterization of PoAstV identified in the present study. (DOC 37 kb

Asymmetric photocurrent extraction in semitransparent laminated flexible organic solar cells

Scalable production methods and low-cost materials with low embodied energy are key to success for organic solar cells. PEDOT(PSS) electrodes meet these criteria and allow for low-cost and all solution-processed solar cells. However, such devices are prone to shunting. In this work we introduce a roll-to-roll lamination method to construct semitransparent solar cells with a PEDOT(PSS) anode and an polyethyleneimine (PEI) modified PEDOT(PSS) cathode. We use the polymer:PCBM active layer coated on the electrodes as the lamination adhesive. Our lamination method efficiently eliminates any shunting. Extended exposure to ambient degrades the laminated devices, which manifests in a significantly reduced photocurrent extraction when the device is illuminated through the anode, despite the fact that the PEDOT(PSS) electrodes are optically equivalent. We show that degradation-induced electron traps lead to increased trap-assisted recombination at the anode side of the device. By limiting the exposure time to ambient during production, degradation is significantly reduced. We show that lamination using the active layer as the adhesive can result in device performance equal to that of conventional sequential coating

Susceptibility of the natural environment to selected pressure factors : case study of the Polish part of the Białka river catchment

Printing solar cell: yield enhanced by laminating the active layer The manufacturing yield of the flexible organic solar cells is enhanced with a new lamination method by solving the shunting problem due to conductive inks. A collaborative team led by Olle Inganäs from Linköping University, Sweden fabricates polymer: PCBM all-organic solar cells in ambient conditions using the active layer as the lamination adhesive. The team shows that reduced exposure to ambient is critical to achieve high device efficiency and suppress degradation. The degraded devices generate asymmetric photocurrent due to the electron traps in the active layer. The reported active layer lamination method not only solves the shunting problem in a number of different polymer: PCBM combinations, but also provides wide tenability and control of the composition and vertical phase separation of the active layer

Relating open-circuit voltage losses to the active layer morphology and contact selectivity in organic solar cells

We demonstrate that voltage losses due to both radiative and non-radiative recombination of charge carriers are strongly dependent on D/A phase separation. By processing the active layer with various solvent additives, we create distinct morphologies that lead to significantly different device open-circuit voltages (VOC), even though the charge transfer state energy (ECT) of the D/A blend remains rather constant. We find that radiative recombination losses are significantly increased for a finely intermixed morphology, due to the large D/A interface area. This leads to a total recombination loss of ECT - qVOC ≈ 0.7 eV. However, considerably smaller losses (0.5 eV), due to suppressed non-radiative recombination, are possible in solar cells where the D/A materials are organized to only allow for selective charge carrier extraction. Using a drift diffusion model, we show that the origin of the reduced non-radiative recombination losses is related to an effect which has not been considered for \u27optimized\u27 solar cells-the suppression of minority carrier diffusion to the \u27wrong\u27 contact. Our results suggest that the built-in field is not sufficiently strong even in \u27optimized\u27 organic solar cells and that selective carrier extraction is critical for further improvements in VOC

Dedoping-induced interfacial instability of poly(ethylene imine)s-treated PEDOT:PSS as a low-work-function electrode

Transparent organic electrodes printed from high-conductivity PEDOT:PSS have become essential for upscaling all-carbon based, low-cost optoelectronic devices. In the printing process, low-work-function PEDOT:PSS electrodes (cathode) are achieved by coating an ultra-thin, non-conjugated polyelectrolyte that is rich in amine groups, such as poly(ethylene imine) (PEI) or its ethoxylated derivative (PEIE), onto PEDOT:PSS surfaces. Here, we mapped the physical and chemical processes that occur at the interface between thin PEIx (indicating either PEI or PEIE) and PEDOT:PSS during printing. We identify that there is a dedoping effect of PEDOT induced by the PEIx. Using infrared spectroscopy, we found that the amine-rich PEIx can form chemical bonds with the dopant, PSS. At lower PSS concentration, PEIx also shows an electron-transfer effect to the charged PEDOT chain. These interface reactions lock the surface morphology of PEDOT:PSS, preventing the redistribution of PSS, and reduce the work function. Subsequent exposure to oxygen during the device fabrication process, on the other hand, can result in redoping of the low-work-function PEDOT:PSS interface, causing problems for printing reproducible devices under ambient conditions.Funding Agencies|Swedish Energy AgencySwedish Energy Agency; Swedish Science Council; Swedish Strategic Research Foundation through the project SiOs; Knut and Alice Wallenberg foundation (KAW) through Wallenberg Scholar grant; Knut and Alice Wallenberg foundation (KAW) through Proof of Concept project for upscaling organic solar cells</p

Energy-effectively printed all-polymer solar cells exceeding 8.61% efficiency

All-polymer solar cells (all-PSCs) have attracted tremendous attention in the past few years due to their unique advantages. However, up to now most of high-efficiency all-PSCs are processed by spin-coating with complicated post treatment processes, which is ill-suited to a large-area roll-to-roll (R2R) technique. In this work, high-efficiency all-PSCs based on PTB7-Th and PNDI-T10 are achieved by one of R2R compatible printing techniques, i.e. doctor-blading, without any annealing treatment. It was found that incorporating an additive into all polymer blends solution can prolong the drying time of all polymer nanocomposites from 120 to 1000 s to form a better bulk heterojunction morphology and a higher crystallinity, which thus reduce charge recombination and show much better electrical impedance spectroscopy parameters. Record-breaking power conversion efficiencies (PCEs) of 8.61% and high fill factors (FF) of 0.71 are achieved by doctor-blading under an extremely process-simple and energy-effective conditions. Moreover, large-area (2.03 cm 2 ) flexible ITO-free all-PSCs by doctor-blading with record-breaking PCEs of 6.65% and FF of 0.65 are realized, which are much higher than conventional fullerene-based ones under the same condition, demonstrating that all-PSCs are more suitable for the flexible device structure and have a bright future towards practical application with R2R manufacture

Intrinsic polarization-sensitive organic photodetector with self-assembled all-polymer heterojunction

Intrinsic polarization-sensitive photodetectors (IPPDs) have attracted considerable attention in recent years due to their simplicity in configuration, making them ideal candidates for compact and integrated polarization-sensitive sensing and imaging systems. Photoactive films with intrinsic optical anisotropy are necessary for IPPDs. This study reports an achievement of photoactive films based on all-polymer heterojunction films with in-plane optical anisotropy using a simple bottom-up self-assembly method. Both the donor (TQ1) and acceptor (N2200) polymers have the same spatial orientation with distinct anisotropy, approaching a dichroic ratio (DR) of 8. Polarization-sensitive light absorption is due to the uniaxially oriented polymer chains, which are dominated by lamellar packing with edge-on orientation. For IPPDs based on this anisotropic all-polymer heterojunction film, a photocurrent anisotropy was found with a polarized photocurrent ratio of 2.6. The detectivity of these IPPDs was found to be 1.9 × 1011 Jones (@ ∼600 nm, 0 V bias). Our work shows that oriented polymer donor-acceptor films fabricated using bottom-up self-assembly have great potential in applications, such as polarization detection