A5058887924- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Perovskite Materials and Applications
- Surface Treatment and Residual Stress
- Thin-Film Transistor Technologies
- Mechanical stress and fatigue analysis
- Organic Light-Emitting Diodes Research
- Erosion and Abrasive Machining
- Railway Engineering and Dynamics
- Metal Alloys Wear and Properties
- Quantum Dots Synthesis And Properties
- Advanced machining processes and optimization
- Energetic Materials and Combustion
- Advanced ceramic materials synthesis
- Diamond and Carbon-based Materials Research
- Healthcare and Venom Research
- Electrical Contact Performance and Analysis
- Tunneling and Rock Mechanics
- High-Velocity Impact and Material Behavior
- Adhesion, Friction, and Surface Interactions
- Laser and Thermal Forming Techniques
- Bee Products Chemical Analysis
- Synthesis and properties of polymers
- Strong Light-Matter Interactions
- Luminescence and Fluorescent Materials
North Carolina State University
2022-2024
University of Michigan–Ann Arbor
2016-2023
Ann Arbor Center for Independent Living
2019-2021
Tokyo University of Agriculture and Technology
2008-2012
Swinburne University of Technology
2011-2012
Central Queensland University
2006
The University of Sydney
2002-2006
Harvard University
2005
University of Technology Sydney
2002-2003
Abstract Organic photovoltaic cells (OPVs) have the potential of becoming a productive renewable energy technology if requirements low cost, high efficiency and prolonged lifetime are simultaneously fulfilled. So far, remaining unfulfilled promise this is its inadequate operational lifetime. Here, we demonstrate that instability NFA solar arises primarily from chemical changes at organic/inorganic interfaces bounding bulk heterojunction active region. Encapsulated devices stabilized by...
High-efficiency organic solar cells are often achieved using toxic halogenated solvents and additives that constrained in industry. Therefore, it is important to develop materials or processing methods enabled highly efficient processed by halogen free solvents. In this paper, we report an innovative method named auxiliary sequential deposition enables 19%-efficiency Our different from the conventional blend casting involves additional of dithieno[3,2-b:2',3'-d]thiophene between depositions...
Series of giant molecule acceptors DY, TY and QY with two, three four small acceptor subunits are synthesized by a stepwise synthetic method used for systematically investigating the influence subunit numbers on structure-property relationship from YDT to polymerized PY-IT. Among these acceptors-based devices, TY-based film shows proper donor/acceptor phase separation, higher charge transfer state yield longer lifetime. Combining highest electron mobility, more efficient exciton dissociation...
Abstract Indoor photovoltaics (IPVs) are garnering increasing attention from both the academic and industrial communities due to pressing demand of ecosystem Internet‐of‐Things. All‐polymer solar cells (all‐PSCs), emerging as a sub‐type organic photovoltaics, with merits great film‐forming properties, remarkable morphological light stability, hold promise simultaneously achieve high efficiency long‐term operation in IPV's application. However, dearth polymer acceptors medium‐bandgap has...
Abstract Cyanation is a common chemical modification strategy to fine‐tune the energy levels and molecular packing of organic semiconductors, especially materials used in solar cells (OSCs). Generally, cyanation modify end groups high‐performance small‐molecule acceptors (SMAs). However, has not been investigated on central backbone SMAs, which could introduce stronger intermolecular interaction enhance π–π stacking for rapid charge transport. This paper, first time, reports new...
Abstract Polymerization of Y6-type acceptor molecules leads to bulk-heterojunction organic solar cells with both high power-conversion efficiency and device stability, but the underlying mechanism remains unclear. Here we show that exciton recombination dynamics polymerized acceptors (Y6-PAs) strongly depends on degree aggregation. While fast rate in aggregated Y6-PA competes electron-hole separation at donor–acceptor (D–A) interface, much-suppressed dispersed is sufficient allow efficient...
We study the optoelectronic properties of a type-II heterojunction (HJ) comprising monolayer transition metal dichalcogenide (TMDC), WS2, and thin film organic semiconductor, 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA). Both theoretical experimental investigations HJ indicate that Frenkel states in layer two-dimensional Wannier-Mott TMDC dissociate to form hybrid charge transfer excitons at interface subsequently into free charges are collected opposing electrodes. A photodiode...
Abstract Amorphous molecular solids are inherently disordered, exhibiting strong exciton localization. Optical microcavities containing such disordered excitonic materials have been theoretically shown to support both propagating and localized exciton‐polariton modes. Here, the ultrastrong coupling of a Bloch surface wave photon excitons in organic thin film at room temperature is demonstrated, where major fraction polaritons states. The delocalized has group velocity as high 3 × 10 7 m s –1...
The energy loss ${E}_{l\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}s}$ seen in organic photovoltaics sets a fundamental limit to their open-circuit voltage, and hence power conversion efficiency. This study compares molecular structures of fullerene nonfullerene acceptors quantifies the relationship between ${E}_{l\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}s}$, exciton binding energy, intra- intermolecular electron-phonon couplings....
The treatment of toluene solvent and DTT additive enables the PBQ6:PYF-T- o -based all-PSC devices with PCE up to 17.06%, which is one highest value in non-halogenated-processed all-PSCs date.
Power conversion efficiency (PCE) of organic solar cells (OSCs) processed by nonhalogenated solvents is unsatisfactory due to the unfavorable morphology. Herein, two new small molecule acceptors (SMAs) Y6-Ph and L8-Ph are synthesized introducing a phenyl end group in inner side chains SMAs Y6 L8-BO, respectively, for overcoming excessive aggregation long-time film forming solvents. First, effect time on property photovoltaic performance Y6, Y6-Ph, studied using commonly used solvents:...
Laser shock peening (LSP) is an innovative surface treatment technique successfully applied to improving fatigue performance of metallic materials. The strength and life the laser peened material can be significantly improved by deep compressive residual stresses being introduced into material. stress distribution along depth attributed a high amplitude wave induced energy pulse. present paper describes finite element method for simulating in metal alloy 35CD4 50 HRC steel single multiple...
Tough organic solar cell (OSC) active layers are necessary to achieve robust, flexible, and stretchable devices. A major challenge is that the brittle small molecule acceptor (SMA) in polymer/SMA bulk heterojunctions results films prone mechanical failure. To improve toughness, we investigate use of a thermoplastic elastomer (styrene-b-ethylene-butylene-styrene) (SEBS) as an additive high-performance photoactive layers. We find consistent transition all measured parameters [e.g., fracture...
Organic photodetectors (OPDs) capable of detecting visible to near-infrared light provide a ubiquitous platform for emerging flexible and wearable electronics. In the process implementing OPDs into Si-based manufacturing process, organic semiconductors undergo ≥ 200 °C thermal stress, leading deterioration photosensing capability. Here, we combine multiscale characterization device physics unravel impact stress on optoelectronics characteristics PTB7-Th:non-fullerene acceptor blends (NFAs:...
Achieving green-solvent solubility of conjugated polymers in truly green solvents such as alcohols has proven to be a significant challenge. In this work, we report the synthesis and characterization three derived from poly[(thiophene)-alt-(6,7-difluoro-2-(2-hexyldecyloxy)quinoxaline)] (PTQ10) with goal developing derivates which are more green-solvent-processable. The traditional alkyl side chains replaced by various oligo(ethylene glycol) (OEG) different architectures, including one linear...
Abstract Orienting polymer semiconductors is desirable to optimize device characteristics, provide insight into microstructure, and magnify subtle phase behavior. Here, a combination of uniaxial strain subsequent heating the donor–acceptor (DA) PBnDT‐FTAZ discovered lead exceptional optical dichroic ratios up 38 (and close 50 near polymer's absorption edge). This alignment achieved due existence previously undetected thermotropic liquid crystal (LC) mesophase. The LC transition, not...
We study the charge transfer (CT) states in small-molecule blend heterojunctions comprising nonpolar donor, tetraphenyldibenzoperiflanthene (DBP), and acceptor, C70, using electroluminescence steady-state time-resolved photoluminescence spectroscopy along with density functional theory calculations. find that CT exciton energy blue shifts as C70 concentration is either decreased or increased away from 50 vol %. At 20 K, increase state lifetime correlated increasing diameter of...
Mixing a sterically bulky, electron-transporting host material into conventional single host-guest emissive layer is demonstrated to suppress phase separation of the matrix while increasing efficiency and operational lifetime deep-blue phosphorescent organic light-emitting diodes (PHOLEDs) with chromaticity coordinates (0.14, 0.15). The bulky enables homogenous mixing molecules comprising suppressing aggregation; significant loss channel nonradiative recombination. By controlling amorphous...
Orienting light-emitting molecules relative to the substrate is an effective method enhance optical outcoupling of organic devices. Platinum(II) phosphorescent complexes enable facile control molecular alignment due their planar structures. Here, orientation Pt(II) during growth emissive layers controlled by two different methods: modifying structure and using structural templating. Molecules whose structures are modified adjusting diketonate ligand Pt complex, dibenzo-(f,h)quinoxaline...
Abstract Understanding chemical degradation at the interface between different layers in an organic photovoltaic device (OPV) is crucial to improving long‐term stability of OPVs. Herein, molecular‐level insights are provided into impact metal top electrodes on interfacial morphology and photoactive PM6:Y6 bulk‐heterojunction (BHJ) OPVs with aluminum (Al) electrode exhibit inferior compared silver (Ag) devices upon thermal annealing, whereby stress induces diffusion both Al Ag atoms BHJ...
Laser shock peening (LSP) is a fatigue enhancement surface treatment for metallic materials. The key beneficial characteristic of LSP the presence compressive residual stresses mechanically produced by waves within materials, which can significantly improve their life and strength. During LSP, laser beam be directed to impact on either one side or two sides target. Generally, when treating thin section, sided used avoid harmful effects such as spalling fracture, may occur only section...
The thermal stability of inverted, halogen-rich non-fullerene acceptor (NFA)-based organic photovoltaics with MoOx as the hole transporting layer is studied at temperatures up to 80 °C. Over time, power conversion efficiency shows a "check-mark" shaped aging pattern, featuring an early decrease, followed by long-term recovery. A high Cl concentration bulk heterojunction (BHJ)/MoOx interface in thermally aged device found using energy dispersive X-ray spectroscopy. photoelectron spectroscopy...
For organic photovoltaic (OPV) devices to achieve consistent performance and long operational lifetimes, semiconductors must be processed with precise control over their purity, composition, structure. This is particularly important for high volume solar cell manufacturing where of materials quality has a direct impact on yield cost. Ternary-blend OPVs containing two acceptor-donor-acceptor (A-D-A)-type nonfullerene acceptors (NFAs) donor have proven an effective strategy improve spectral...