Abstract Charge transport and nongeminate recombination are investigated in two solution‐processed small molecule bulk heterojunction solar cells consisting of diketopyrrolopyrrole (DPP)‐based donor molecules, mono‐DPP bis‐DPP, blended with [6,6]‐phenyl‐C71‐butyric acid methyl ester (PCBM). While the bis‐DPP system exhibits a high fill factor (62%) suffers from pronounced voltage dependent losses, which limit both (46%) short circuit current. A method to determine average charge carrier...

In this report, we demonstrate that parasitic leakage currents dominate the current voltage characteristics of organic solar cells measured under illumination intensities less than one sun when device shunt resistance is too low (<106 Ω cm2). The implications such effects on common interpretations light intensity dependence cell open circuit voltage, fill factor, short current, and power conversion efficiency are discussed in detail.

By combining the molecular donor p-DTS(FBTTh2)2 with a readily produced perylene diimide acceptor we are able to achieve power conversion efficiency of 3.0%, making this one most efficient non-fullerene organic solar cells date. The reduced present system compared use phenyl-C71-butyric acid methyl ester as an electron is shown primarily be related significant reduction in internal quantum efficiency. These results indicate potential small-molecule:non-fullerene bulk-heterojunction...

ABSTRACT Recent measurements in poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films show that capacitance scales with film volume. We discuss the ramifications of this finding and propose a simple model describes terms sites which ions injected from electrolyte replace holes are extracted by metal contact. volumetric is inversely proportional to average distance between these sites. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Phys. , 54 1433–1436

Analysis of measured charge-carrier mobilities and fill factors in solution-processable small-molecule bulk-heterojunction solar cells reveals that order to achieve a high FF, the hole electron must be >10−4 cm 2 V−1 s−1. Neat-film mobility measurements are also found useful predictor maximum blend film FF obtained cells. As service our authors readers, this journal provides supporting information supplied by authors. Such materials peer reviewed may re-organized for online delivery, but not...

Morphological control over the bulk heterojunction (BHJ) microstructure of a high‐efficiency small molecule photovoltaic system is demonstrated using both thermal treatment and solvent additive processing. Single crystal X‐ray diffraction utilized to understand molecular interactions in solid state BHJ morphology examined bright field, high‐resolution, cross‐section transmission electron microscopy techniques. Controlling domain size, while maintaining good order within semiconducting donor...

Connections are delineated between solar-cell performance, charge-carrier mobilities, and morphology in a highperformance molecular solar cell. The observations show that maximizing the relative phase purity structural order while simultaneously limiting domain size may be essential for achieving optimal performances solution-processed small-molecule cells .

An implantable microfluidic ion pump prevents seizures in a mice by delivery of inhibitory neurotransmitters to the seizure source.

Organic solar cells utilizing the small molecule donor 7,7′‐(4,4‐bis(2‐ethylhexyl)‐4H‐silolo[3,2‐b:4,5‐b′]dithiophene‐2,6‐diyl)bis(6‐fluoro‐4‐(5′‐hexyl‐[2,2′‐bithiophen]‐5‐yl)benzo[c][1,2,5] thiadiazole) ( p ‐DTS(FBTTh 2 ) and polymer acceptor poly{[N,N′‐bis(2‐octyldodecyl)‐1,4,5,8‐naphthalenedicarboximide‐2,6‐diyl]‐alt‐5,5′‐(2,2′‐bithiophene)}(P(NDI2OD‐T2)) are investigated a power conversion efficiency of 2.1% is achieved. By systematic study bulk heterojunction (BHJ) organic photovoltaic...

Whereas the role of molecularly mixed domains in organic photovoltaic devices for charge generation is extensively discussed literature, impact on recombination and thus fill factor largely unexplored. Here, a combination soft X‐ray techniques enables quantification phases at multiple length scales to reveal their regarding highly efficient solution processed small molecule system...

The light intensity dependence of the main photoelectrical parameters nonfullerene small‐molecule bulk heterojunction (BHJ) solar cells p‐DTS(FBTTh 2 ) :perylene diimide (T1:PDI) shows that nongeminate recombination losses play an important role in this system. A simple approach for quantitative analysis capacitance spectroscopy data organic BHJ cells, which allows to determine density free charge carriers as a function applied bias under standard working conditions, is demonstrated. Using...

We report a series of solution-processable, small-molecule, donor materials based on an architecture consisting two diketopyrrolopyrrole (DPP) cores with different aromatic π-bridges between the DPP units and end-capping groups. In general, this leads to desirable light absorption electronic levels for materials. Out compounds investigated, material hydrolyzed dithieno(3,2-b;2′,3′-d)silole (SDT) core 2-benzofuran (BFu) end capping groups most favorable properties solar cells, capable...

Implantable devices offer an alternative to systemic delivery of drugs for the treatment neurological disorders. A microfluidic ion pump (µFIP), capable delivering a drug without solvent through electrophoresis, is developed. The device characterized in vitro by γ-amino butyric acid target solution, and demonstrates low-voltage operation, high drug-delivery capacity, ON/OFF ratio. It also demonstrated that suitable cortical vivo manipulating local concentration animal model altering neural...

Two new high-performance DPP-containing donor molecules employing a molecular architecture with three DPP chromorphores (tri-DPP) in conjugated backbones are synthesized and characterized. The two tri-DPP only structural difference on alkyl substitutions, when blended PC71BM, lead to power conversion efficiencies up 4.8 5.5%, respectively.

The field of organic photovoltaics has recently produced highly efficient single‐junction cells with power conversion efficiency >10%, yet the open‐circuit voltage ( V OC ) remains relatively low in many high performing systems. An accurate picture density states (DOS) working solar is crucial to understanding sources loss, but difficult obtain experimentally. Here, tail DOS characterized a number small molecule bulk heterojunction from charge dependence , and directly compared disorder...

Scalable electronic brain implants with long-term stability and low biological perturbation are crucial technologies for high-quality brain–machine interfaces that can seamlessly access delicate hard-to-reach regions of the brain. Here, we created “NeuroRoots,” a biomimetic multi-channel implant similar dimensions (7 μm wide 1.5 thick), mechanical compliance, spatial distribution as axons in Unlike planar shank implants, these devices consist number individual electrode “roots,” each tendril...

The effects of processing conditions on charge transport and voltage dependent recombination losses in one the most efficient solution-processed small molecule solar cell systems reported to date are studied. With careful control blend film morphology, geminate (GR) can be completely overcome while reducing bimolecular (BMR) allow for generation collection photogenerated carriers. These results highlight that a field-dependent mechanism is not necessarily an inherent molecular property.

Abstract The challenge of treating neurological disorders has motivated the development implantable devices that can deliver treatment when and where it is needed. This study presents a novel brain implant capable electrophoretically delivering drugs recording local neural activity on surface brain. drug delivery made possible by integration microfluidic ion pump (µFIP) into conformable electrocorticography (ECoG) device with cites embedded next to outlets. µFIP ECoG high capacity several...

Advantages of semiconducting small molecules-as opposed to polymers-include synthetic simplicity, monodispersity, low cost, and ease purification. One purported disadvantage small-molecule films is reduced mechanical robustness. This paper measures the tensile modulus crack-onset strain for pure high-performance solution-processable donors 7,7'-[4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl]bis[6-fluoro-4-(5'-hexyl-[2,2'-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole]...

Spinal cord stimulation is one of the oldest and most established neuromodulation therapies. However, today, clinicians need to choose between bulky paddle-type devices, requiring invasive surgery under general anesthetic, percutaneous lead-type which can be implanted via simple needle puncture local anesthetic but offer clinical drawbacks when compared with paddle devices. By applying photo- soft lithography fabrication, we have developed a device that features thin, flexible electronics...

Abstract Bioelectronics hold the key for understanding and treating disease. However, achieving stable, long‐term interfaces between electronics body remains a challenge. Implantation of bioelectronic device typically initiates foreign response, which can limit recording stimulation efficacy. Techniques from regenerative medicine have shown high propensity promoting integration implants with surrounding tissue, but these lack capabilities sophisticated actuation afforded by electronics....

Abstract Electrocorticography is an established neural interfacing technique wherein array of electrodes enables large-area recording from the cortical surface. commonly used for seizure mapping however implantation electrocorticography arrays a highly invasive procedure, requiring craniotomy larger than implant area to place device. In this work, flexible thin-film electrode are combined with concepts soft robotics, realize device that can change shape via integrated fluidic actuators. We...

The purpose of this study was to characterize the repair tissue that develops after removal a portion patellar ligament for use as graft. A six-millimeter-wide strip obtained from central with tibial and bone plugs one knee (stifle joint) eight goats. formed in defect characterized terms its structural, material, histological, ultrastructural properties twenty-one months operation. contralateral served control. Representative specimens were taken proximal, middle, distal portions control...