A5038714363- Organic Electronics and Photovoltaics
- Perovskite Materials and Applications
- Conducting polymers and applications
- Photochemistry and Electron Transfer Studies
- Quantum Dots Synthesis And Properties
- Luminescence and Fluorescent Materials
- Molecular Junctions and Nanostructures
- Organic Light-Emitting Diodes Research
- Advanced Photocatalysis Techniques
- Advancements in Battery Materials
- Porphyrin and Phthalocyanine Chemistry
- Advanced Battery Materials and Technologies
- Chalcogenide Semiconductor Thin Films
- Electrochemical Analysis and Applications
- Advanced Battery Technologies Research
- Radical Photochemical Reactions
- CO2 Reduction Techniques and Catalysts
- Spectroscopy and Quantum Chemical Studies
- Nanowire Synthesis and Applications
- Graphene research and applications
- Thin-Film Transistor Technologies
- Nanoplatforms for cancer theranostics
- Chemical Reactions and Mechanisms
- Luminescence Properties of Advanced Materials
- bioluminescence and chemiluminescence research
University of Washington
2014-2025
Clean Energy (United States)
2019-2024
Technical University of Munich
2020
Polish Academy of Sciences
2020
Institute of Physics
2020
Seattle University
2015
University of Southern California
2009-2011
We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as conductive electrodes (TCE) in organic photovoltaic cells. Graphene were synthesized CVD, transferred to substrates, evaluated solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key our success is continuous nature CVD films, which led minimal surface...
Nanocrystals of phase-pure tin(II) selenide (SnSe) were synthesized via a solution-phase route employing stoichiometric amounts di-tert-butyl diselenide as novel and facile selenium source. The direct band gap the resulting nanocrystals (E(g) = 1.71 eV) is significantly blue-shifted relative to bulk value 1.30 eV), likely consequence quantum confinement from relatively small average diameter (mu(D) < 20 nm). Preliminary solar cell devices incorporating SnSe into...
All-inorganic cesium lead bromide (CsPbBr3) perovskite quantum dots (QDs) have recently emerged as highly promising solution-processed materials for next-generation light-emitting applications. They combine the advantages of QD and materials, which makes them an attractive platform achieving high optical gain with stability. Here, we report ultralow lasing threshold (0.39 μJ/cm2) from a hybrid vertical cavity surface emitting laser (VCSEL) structure consisting CsPbBr3 thin film two...
Solar hydrogen generation from water represents a compelling component of future sustainable energy portfolio. Recently, chemically robust heptazine-based polymers known as graphitic carbon nitrides (g-C3N4) have emerged promising photocatalysts for evolution using visible light while withstanding harsh chemical environments. However, since g-C3N4 electron-transfer dynamics are poorly understood, rational design rules improving activity remain unclear. Here, we use and near-infrared...
According to Hund's rule, the lowest triplet state (T1) is lower in energy than excited singlet (S1) closed-shell molecules. The exchange integral lowers of and raises same orbital character, leading a positive singlet-triplet gap (ΔST). Exceptions are known for biradicals charge-transfer states large molecules which highest occupied molecular (HOMO) unoccupied (LUMO) spatially separated, resulting small integral. In present work, we discovered with ADC(2), CC2, EOM-CCSD, CASPT2 calculations...
Multichromophoric arrays provide one strategy for assembling molecules with intense absorptions across the visible spectrum but are generally focused on systems that efficiently produce and manipulate singlet excitations therefore burdened by restrictions of (a) unidirectional energy transfer (b) limited tunability lowest molecular excited state. In contrast, we present here a multichromophoric array based four boron dipyrrins (BODIPY) bound to platinum benzoporphyrin scaffold exhibits...
Since the inception of heterojunction organic photovoltaic research organic/organic interface has been thought to play a crucial role in determining magnitude open-circuit voltage. Yet, task defining molecular properties dictating photovoltage delivered by these devices, that employ mixed or neat layers different molecules convert incident photons electricity, is still an active area research. This will likely be key step designing new materials required for improving future device...
High-dielectric constant side-chain polymers that show reduced non-geminate recombination in heterojunction solar cells are reported. Active layer with high dielectric side-chains increased performance over alkyl polymers. The doubling efficiency is attributed to suppressed recombination. As a service our authors and readers, this journal provides supporting information supplied by the authors. Such materials peer reviewed may be re-organized for online delivery, but not copy-edited or...
Abstract Device performance and photoinduced charge transfer are studied in donor/acceptor blends of the oxidation‐resistant conjugated polymer poly[(4,8‐bis(2‐hexyldecyl)oxy)benzo[1,2‐b:4,5‐b′]dithiophene)‐2,6‐diyl‐alt‐(2,5‐bis(3‐dodecylthiophen‐2‐yl)benzo[1,2‐d;4,5‐d′]bisthiazole)] (PBTHDDT) with following fullerene acceptors: [6,6]‐phenyl‐C 71 ‐butyric acid methyl ester (PC BM); 61 indene‐C 60 bis ‐adduct IC BA). Power conversion efficiency improves from 1.52% BA‐based solar cells to...
We demonstrate planar organic solar cells consisting of a series complementary donor materials with cascading exciton energies, incorporated in the following structure: glass/indium-tin-oxide/donor cascade/C60/bathocuproine/Al. Using tetracene layer grown descending energy cascade on 5,6-diphenyl-tetracene and capped 5,6,11,12-tetraphenyl-tetracene, where accessibility π-system each material is expected to influence rate parasitic carrier leakage charge recombination at donor/acceptor...
A systematic study of the preparation porphyrins with extended conjugation by meso,β-fusion polycyclic aromatic hydrocarbons (PAHs) is reported. The meso-positions 5,15-unsubstituted were readily functionalized PAHs. Ring fusion using standard Scholl reaction conditions (FeCl(3), dichloromethane) occurs for perylene-substituted to give a porphyrin β,meso annulated perylene rings (0.7:1 ratio syn and anti isomers). naphthalene, pyrene, coronene derivatives do not react under but are fused...
We use dipolar phosphonic acid self-assembled monolayers (PA SAMs) to modify the work function of hole-extracting contact in polymer/fullerene bulk heterojunction solar cells. observe a linear dependence open-circuit voltage (VOC) these organic photovoltaic devices on modified indium tin oxide (ITO) when using donor polymer with deep-lying ionization energy. With specific SAMs, we can obtain VOC values exceeding those obtained common poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)...
To gain mechanistic understanding of heptazine-based photochemistry, we synthesized and studied 2,5,8-tris(4-methoxyphenyl)-1,3,4,6,7,9,9b-heptaazaphenalene (TAHz), a model molecular photocatalyst chemically related to carbon nitride. On the basis time-resolved photoluminescence (TR-PL) spectroscopy, kinetically reveal new feature that emerges in aqueous dispersions TAHz. Using global target analysis, spectrally resolve emission be blue shifted from steady-state luminescence, observe fast...
We study charge recombination via triplet excited states in donor/acceptor organic solar cells and find that, contrary to intuition, high internal quantum efficiency (IQE) can be obtained polymer/fullerene blend devices even when the polymer state is significantly lower energy than intermolecular transfer (CT) state. Our model donor system comprises copolymer PIDT-PhanQ: poly(indacenodithiophene-co-phenanthro[9,10-b]quinoxaline), which blended with phenyl-C71-butyric acid methyl ester...
Conjugated polymers blended with nanocrystal quantum dots are interesting as solution processable active layers for infrared light harvesting in thin film solar cells. We study photocurrent generation processes hybrid polymer/quantum dot photovoltaics by comparing device performance and photoinduced absorption (PIA) spectra across blends of three different conjugated polymers, poly(2,3-bis(2-(hexyldecyl)-quinoxaline-5,8-diyl-alt-N-(2-hexyldecyl)-dithieno[3,2-b:2′,3′-d]pyrrole) (PDTPQx-HD),...
Using an analysis based on Marcus theory, we characterize losses in open-circuit voltage (VOC) due to changes charge-transfer state energy, electronic coupling, and spatial density of states a series polymer/fullerene solar cells. We use indacenodithiophene polymers their selenium-substituted analogs as electron donor materials fullerenes the acceptors. By combining device measurements spectroscopic studies (including subgap photocurrent, electroluminescence, and, importantly, time-resolved...
Abstract Infrared organic photodetector materials are investigated using transient absorption spectroscopy, demonstrating that ultrafast charge generation assisted by polymer aggregation is essential to compensate for the energy gap law, which dictates excited state lifetimes decrease as band narrows. Short sub‐picosecond singlet exciton measured in a structurally related series of infrared‐absorbing copolymers consist alternating cyclopentadithiophene electron‐rich “push” units and strong...
Organic photovoltaics (OPVs) constitute a promising new technology due to their low production costs. However, OPV efficiencies remain because excitons typically diffuse only ∼5-20 nm during lifetime, limiting the effective thickness of light-absorbing layer. One strategy improve OPVs is increase exciton lifetimes by converting them into triplet states, which persist 10(3)-10(5) times longer than singlet excitons. We present femtosecond transient absorption and steady-state photovoltaic...
We use photoinduced absorption (PIA) spectroscopy to investigate pathways for photocurrent generation in hybrid organic/inorganic quantum dot bulk heterojunction solar cells. study blends of the conjugated polymer poly(2,3-bis(2-(hexyldecyl)quinoxaline-5,8-diyl-alt-N-(2-hexyldecyl)dithieno[3,2-b:2′,3′-d]pyrrole) (PDTPQx-HD) with PbS dots and find that positively charged polarons are formed on following selective photoexcitation dots. This result provides a direct spectroscopic fingerprint...
For the first time on nanoparticle-based Si electrodes, we monitor electrochemical reduction products of ethylene carbonate (EC) and fluoroethylene (FEC) using interface-sensitive operando spectroelectrochemical sum-frequency generation (SFG). We observe SFG signatures that suggest carbon monoxide (CO) evolution nano-Si proceeds at distinct lithiation potentials for different electrolyte solvents. EC to yield CO-associated species occurs associated with silicon's most highly lithiated state...
The transfer of protons and electrons is key to energy conversion storage, from photosynthesis fuel cells. Increased understanding control these processes are needed. A new anthracene-phenol-pyridine molecular triad was designed undergo fast photoinduced multiple-site concerted proton-electron (MS-CPET), with the phenol moiety transferring an electron photoexcited anthracene a proton pyridine. Fluorescence quenching transient absorption experiments in solutions glasses show rapid MS-CPET (3.2 × 10