A5046560705- Organic Electronics and Photovoltaics
- Conducting polymers and applications
- Perovskite Materials and Applications
- Thin-Film Transistor Technologies
- Advanced Thermoelectric Materials and Devices
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Molecular Junctions and Nanostructures
- Solid-state spectroscopy and crystallography
- Quantum Dots Synthesis And Properties
- Organic Light-Emitting Diodes Research
- Ionic liquids properties and applications
- Force Microscopy Techniques and Applications
- Advanced Sensor and Energy Harvesting Materials
- Analytical Chemistry and Sensors
- 2D Materials and Applications
- Semiconductor materials and interfaces
- Fullerene Chemistry and Applications
- Nanofabrication and Lithography Techniques
- Organic and Molecular Conductors Research
- Advanced Memory and Neural Computing
- Chalcogenide Semiconductor Thin Films
- Nanowire Synthesis and Applications
- Advanced Polymer Synthesis and Characterization
- Transition Metal Oxide Nanomaterials
University of California, Santa Barbara
2016-2025
Santa Barbara City College
2014-2021
University of California System
2009-2020
Mitsubishi Chemical (Germany)
2020
Division of Materials Research
2014-2019
Material (Belgium)
2014-2019
California NanoSystems Institute
2011-2018
Dalhousie University
2015
Mitsubishi Group (Japan)
2015
National Institute of Standards and Technology
2007-2009
This paper describes an experimentally simple system for measuring rates of electron transport across organic thin films having a range molecular structures. The uses metal−insulator−metal junction based on self-assembled monolayers (SAMs); it is particularly easy to assemble. consists SAM supported silver film (Ag-SAM(1)) in contact with second the surface drop mercury (Hg-SAM(2))that is, Ag-SAM(1)SAM(2)-Hg junction. SAM(1) and SAM(2) can be derived from same or different thiols. current...
Abstract Developing a better understanding of the evolution morphology in plastic solar cells is key to designing new materials and structures that achieve photoconversion efficiencies greater than 10%. In most extensively characterized system, poly(3‐hexyl thiophene) (P3HT):[6,6]‐phenyl‐C 61 ‐butyric‐acid‐methyl‐ester (PCBM) bulk heterojunction, origins blend during processes such as thermal annealing are not well understood. this work, we use model bilayer P3HT PCBM, develop more complete...
Ternary bismuth halides form an interesting functional materials class in the context of closely related Pb halide perovskite photovoltaics, especially given significantly reduced toxicity Bi when compared with Pb. The compounds A3Bi2I9 (A = K, Rb, Cs) examined here crystallize two different structure types: layered defect-perovskite K3Bi2I9 type, and Cs3Cr2Cl9 type. latter type features isolated Bi2I93– anions. Here, crystal structures ternary iodides are redetermined a corrected structural...
Abstract Organic semiconductors are emerging as a viable alternative to amorphous silicon in range of thin‐film transistor devices. With the possibility formulate these p‐type materials inks and subsequently print into patterned devices, organic‐based transistors offer significant commercial advantages for manufacture, with initial applications such low performance displays simple logic being envisaged. Previous limitations both air stability electrical now overcome small molecule...
This paper describes a prototype of an integrated fluorescence detection system that uses microavalanche photodiode (microAPD) as the photodetector for microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The device consisted reusable and disposable was using rapid prototyping. first step procedure fabrication channels PDMS encapsulation multimode optical fiber (100-microm core diameter) PDMS; tip placed next to side wall one channels. used couple light into microchannel...
The development of organic semiconductors for use in thermoelectrics requires the optimization both their thermopower and electrical conductivity. Here two fundamentally different doping mechanisms are used to investigate thermoelectric properties known high hole mobility polymers: poly 3‐hexylthiophene (P3HT), poly(2,5 ‐ bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐C 14 ), poly(2,5‐bis(thiphen‐2‐yl)‐(3,7‐diheptadecantyltetrathienoacene)) (P2TDC 17 ‐FT4). small molecule...
The thermoelectric properties of a highperformance electron-conducting polymer, (P(NDIOD-T2), extrinsically doped with dihydro-1H-benzoimidazol-2-yl (NDBI) derivatives, are reported. highest power factor that has been reported for solution-processed n-type polymer is achieved; and it concluded engineering polymerdopant miscibility essential the development organic thermoelectrics.
Poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT, is a semiconducting polymer that forms thin film transistors (TFTs) with high field effect mobility on silicon dioxide dielectrics are treated alkyltrichlorosilanes (∼0.2 to 0.5 cm2/V s) but TFTs poor bare (<0.005 s). The microstructure of spin-coated films PBTTT these surfaces was studied using synchrotron X-ray diffraction and atomic force microscopy. crystallizes lamellae π-stacked chains both surfaces. crystalline domains...
The synthesis of regioregular poly(3-hexyl)selenophene is reported, and its optical electrical properties are compared to those poly(3-hexyl)thiophene.
High performance, solution processable semiconductors are critical to the realization of low cost, large area electronics. We show that a signature molecular packing motifside-chain interdigitationcorrelates high performance for and important class organic semiconductors. The side chains recently developed copolymers poly(alkylthiophenes) can do interdigitate substantially, whereas they not in most common form extensively studied, lower poly(alkythiophenes). Side-chain interdigitation...
The orientational correlation length of domains in a semiconducting polymer controls its thermoelectric performance.
The study of thermoelectric materials spans condensed matter physics, science and engineering, solid-state chemistry. diversity the participants inherent complexity topic mean that it is difficult, if not impossible, for a researcher to be fluent in all aspects field. This review, which grew out one-week summer school graduate students, aims provide an introduction practical guidance selected conceptual, synthetic, characterization approaches craft common umbrella language, theory,...
Solvent additives such as diiodooctane (DIO) are becoming ubiquitous in processing high performance organic photovoltaic (OPV) active layers. Here, we investigate the effects of DIO on long-term stability layer by studying photodegradation under ambient white light illumination polymer PTB7-Th pure thin films and blend with PC71BM. Using X-ray fluorescence, directly detect iodine films, indicating presence residual after casting from solution. Additionally, show that this dramatically...
Doping of thin films semiconducting polymers provides control their electrical conductivity and thermopower. The rises nonlinearly with the carrier concentration, there is a lack understanding detailed factors that lead to this behavior. We report study morphological effects doping on poly(3-hexylthiophene) (P3HT) doped small molecule 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). Resonant soft X-ray scattering shows morphology P3HT not strongly changed by infiltration F4TCNQ...
Transistor measurements can overstate organic semiconductor charge carrier mobility
Abstract By including trap‐limited recombination in a time‐domain drift‐diffusion model of P3HT:PCBM solar cell, experimental transient photocurrent (TPC) measurements across the current–voltage ( J – V ) curve both light and dark can be reproduced. Using same set parameters, steady‐state curves charge‐extraction data are also The is validated by predicting rate at open circuit comparing results with as measured photovoltage (TPV) measurement technique. It demonstrated that model, which...
A new class of high-performance n-type organic thermoelectric materials, self-doping perylene diimide derivatives with modified side chains, is reported. These materials achieve the highest performance solution-processed reported to date, power factors as high 1.4 μW/mK2. results demonstrate that molecular design a promising strategy for enhancing performance. As service our authors and readers, this journal provides supporting information supplied by authors. Such are peer reviewed may be...
Hybrid halide double perovskites are a class of compounds attracting growing interest because their richness structure and property. Two-dimensional (2D) derivatives hybrid formed by the incorporation organic spacer cations into three-dimensional (3D) perovskites. Here, we report series seven new layered perovskite halides with propylammonium (PA), octylammonium (OCA), 1,4-butyldiammonium (BDA) cations. The general formulas AmMIMIIIX8 (single-layered Ruddlesden-Popper type m = 4 A PA or OCA,...
Abstract This roadmap includes the perspectives and visions of leading researchers in key areas flexible printable electronics. The covered topics are broadly organized by device technologies (sections 1–9), fabrication techniques 10–12), design modeling approaches 13 14) essential to future development new applications leveraging electronics (FE). interdisciplinary nature this field involves everything from fundamental scientific discoveries engineering challenges; synthesis materials via...
Transformative and reconstructive reactions impart significant structural changes at particle boundaries of hybrid perovskites, which influence environmental stability optoelectronic properties these materials. Here, we investigate the moisture-induced transformative in formamidinium(FA)-based perovskites FAPbX3 (X = I, Br) show that ambient materials can be adjusted from a few hours to several months. For FAPbI3, roles water vapor, size, light illumination on kinetic pathways cubic (α)...