About

Howard Katz is a professor of materials science and engineering at Johns Hopkins University, with a joint appointment in the Department of Chemistry at the Krieger School of Arts and Sciences. He is a pioneer in the fields of organic electronics and photonics, with research interests that include organic/hybrid materials, organic semiconductors, photonic polymers, conjugated compounds, molecular recognition, self-assembly, fabrication approaches, high-field devices, chemical sensing, energy conversion, and logic devices. Katz established the structural, physical, and synthetic organic chemical principles for several material classes, including molecular semiconductors and nonlinear optical polymers, guiding their development from scientific discovery to widespread application. He was the first to report the value and methodology of organic semiconductor syntheses that avoid impurities responsible for heterogeneity, and introduced rigid, strongly assembling electron donor subunits that are now key components in conducting polymers and printable organic semiconductors. Katz also promoted the idea that the combination of material properties and device architecture in organic field-effect transistors is highly suited for chemical detection, publishing the first paper on this application. His recent work focuses on charge carrier density at organic semiconductor-dielectric interfaces, biosensor and vapor sensor performance enhancements, and the use of static-charged polymer structures to increase conductivity and thermoelectric activity. With 57 U.S. patents, Katz was named to the National Academy of Inventors in 2017 and has received two R&D 100 Awards. He has served as an associate editor for the Journal of Materials Research and on editorial boards for Chemistry of Materials, ACS Applied Materials and Interfaces, and MRS Communications. Katz earned his ScB in chemistry, humanities, and science from MIT in 1978 and a PhD in organic chemistry from UCLA in 1982. Before joining Johns Hopkins in 2004, he worked at AT&T Bell Laboratories (Lucent Technologies).

Research topics

• Materials science
• Optoelectronics
• Chemistry
• Nanotechnology
• Chemical engineering

Selected publications

• Evolution of Acetylacetone from Solution to Film in Indium Nitrate Combustion Sol-Gel

  ChemRxiv · 2026-02-05

  articleOpen access

  This study investigates the evolution of acetylacetone (AcAc) fuel in indium nitrate (Innitrate) combustion sol-gel solution and spin-coated films. The combustion mechanism is studied by varying the AcAc-to-nitrate ratios, referencing pure In-nitrate, pure AcAc, and In(AcAc)3, in which AcAc molecules are fully chelated to indium. Fourier transform infrared (FTIR) spectra reveal that the functional groups present in the In-nitrate solution are nitrate and hydroxyl. With the addition of AcAc, coordinated keto and enol peaks are also observed along with coordinated nitrate peaks, indicating AcAc and nitrate are both coordinated with indium. However, when spin coating the In-nitrate sol-gel solution to form a film, FTIR spectra show peaks corresponding to water, ammonia, and nitrate only, but no keto/enol peaks associated with indium-coordinated AcAc in the sol-gel films. Thus, AcAc is absent from the film, even though it was coordinated in the precursor solution. On the other hand, AcAc is retained in the film when it is made from an In(AcAc)3 solution without nitrate. X-ray photoelectron spectroscopy results corroborate the FTIR findings. Through drying and evaporation studies, we determine that AcAc leaves the In-nitrate sol-gel solutions with the 2-methoxyethanol solvent during spin coating. This study sheds light on the role of AcAc as a fuel and the combustion sol-gel process in thin films.

  PublisherOA PDFDOI

• Interfacial Potential Transduction for Diagnostics

  ArXiv.org · 2026-03-24

  articleOpen access

  A major barrier to decentralized, near-patient diagnostics is the lack of a signal transduction modality that is both analytically precise and accessible at the point of care. Optical readouts remain instrument-dependent and difficult to miniaturize, while compact electrochemical readouts are prone to matrix-derived signal distortion, limiting their biomarker coverage in real clinical settings. Here, we define interfacial potential transduction as a standardized electrical modality for portable, clinical-grade diagnostics across diverse assay formats. A mechanistic framework identifying key sample matrix parameters within the interfacial potentials transduction system enables control of biofluid-derived interference, and is demonstrated in a widely accessible lateral flow immunoassay format through quantitative detection of estradiol, progesterone, and luteinizing hormone in human plasma with high correlation (r2 > 0.97) to clinical analyzers. Broader applicability across representative diagnostic sectors is further demonstrated through exceptional performance including glucose quantification for biochemical analysis with limit of detection (LOD) of 0.92 ug/dL, HIV p24 capsid protein under an immunomagnetic separation workflow (LOD = 44.8 fg/mL), and hepatitis B virus detection within 5 min via loop-mediated isothermal amplification for molecular diagnostics. Together, these results establish interfacial potentials transduction as a unified diagnostic paradigm for near-patient deployment beyond optical and electrochemical approaches.

  PublisherOA PDF

• Interfacial Potential Transduction for Diagnostics

  arXiv (Cornell University) · 2026-03-24

  preprintOpen access

  A major barrier to decentralized, near-patient diagnostics is the lack of a signal transduction modality that is both analytically precise and accessible at the point of care. Optical readouts remain instrument-dependent and difficult to miniaturize, while compact electrochemical readouts are prone to matrix-derived signal distortion, limiting their biomarker coverage in real clinical settings. Here, we define interfacial potential transduction as a standardized electrical modality for portable, clinical-grade diagnostics across diverse assay formats. A mechanistic framework identifying key sample matrix parameters within the interfacial potentials transduction system enables control of biofluid-derived interference, and is demonstrated in a widely accessible lateral flow immunoassay format through quantitative detection of estradiol, progesterone, and luteinizing hormone in human plasma with high correlation (r2 > 0.97) to clinical analyzers. Broader applicability across representative diagnostic sectors is further demonstrated through exceptional performance including glucose quantification for biochemical analysis with limit of detection (LOD) of 0.92 ug/dL, HIV p24 capsid protein under an immunomagnetic separation workflow (LOD = 44.8 fg/mL), and hepatitis B virus detection within 5 min via loop-mediated isothermal amplification for molecular diagnostics. Together, these results establish interfacial potentials transduction as a unified diagnostic paradigm for near-patient deployment beyond optical and electrochemical approaches.

  PublisherDOI

• Incorporation and electronic sensing device effects of aniline functionality in diketopyrrolopyrrole–thiophene semiconducting polymers

  Journal of Materials Chemistry C · 2025-01-01 · 2 citations

  articleOpen accessCorresponding

  The first synthesis of amine- or aniline-substituted thiophene polymers is reported, and field-effect transistor electronic responses to acetone are shown.

  PublisherDOI

• Bayesian optimization of solution-processed thermoelectric polymers using a database of ab initio electronic structure data

  Research Square · 2025-02-07

  preprintOpen access
  PublisherOA PDFDOI

• Spectroscopic, morphological, and dielectric distinctions between a conjugated polymer and its incorporated monomer in field-effect transistors and capacitors

  Journal of Applied Physics · 2025-06-04

  articleOpen accessSenior author

  We investigate the effects of incorporating the monomer 2,5-bis(3-dodecylthiophen-2-yl)thieno[3,2-b]thiophene (BTTT) into thin films of its corresponding polymer, poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT). We examine how this incorporation influences the film's morphology, charge storage capabilities, and dielectric properties. In tri-layer dielectric organic field-effect transistor devices with pentacene as the semiconductor layer, the addition of BTTT to the PBTTT-polystyrene dielectric layer results in increased drain currents and unique threshold voltage shift behaviors, indicating enhanced charge storage capabilities. The key step in this mechanism is that a constant portion of charge-stabilizing entities is generated continuously with the presence of applied voltage. Capacitance measurements show a peak in charge storage at low BTTT concentrations, followed by a decrease at higher concentrations. Notably, dielectric strength analysis using Weibull statistics indicates that films with 20% BTTT content exhibit higher voltage tolerance compared to pure PBTTT or polystyrene films. Spectroscopy and x-ray diffraction analysis reveal that BTTT addition compromises the original ordering of the PBTTT, with higher concentrations leading to more significant disruption, even though distinguishable BTTT domains are formed. We propose a mechanism where BTTT/PBTTT clusters form charge-stabilizing entities, leading to improved charge storage capability and dielectric strength. These findings provide insights into the distinct contributions of monomers in conjugated polymer films and their potential applications in organic electronic devices.

  PublisherDOI

• High Energy Density and Increased Efficiency in Polymer Capacitors with Dilute Blended Electroactive Small Molecules

  ACS Applied Materials & Interfaces · 2025-12-20

  articleSenior authorCorresponding

  The energy storage density (Ue) of a capacitor is governed by its dielectric constant (εr) and breakdown strength (Eb). In this work, single-layer capacitors of the wide-bandgap-insulating polymers polystyrene (PS), polycarbonate (PC), and poly(methyl methacrylate) (PMMA) are fabricated on indium tin oxide (ITO)-coated borosilicate glass substrates with gold top-contacts. Dielectric layers approximately 2–5 μm thick are spin-coated and deposited on the ITO-coated substrates. Dilute concentrations of the small molecules dibenzotetrathiafulvalene (DBTTF), tetrakis(methylthio)tetrathiafulvalene (TMT-TTF), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and 1,3,4,5,7,8-hexafluorotetracyanonaphthoquinodimethane (F6TCNNQ) are solution-blended into each dielectric layer, and their effects on device performance are analyzed. When added in concentrations ranging from 0.01 to 1 wt % with respect to the concentration of polymer in the spinning solution, it is found in nearly all cases that these small molecules enhance the breakdown electric field strength of the polymer capacitors and as a result improve their maximum energy density by as much as 190% relative to control devices with no additives present. A maximum breakdown electrical field strength of 850 MV/m and a corresponding energy density of 16.2 J/cm3 are observed in PMMA with 0.1 wt % F4TCNQ capacitors, the best-performing devices in this study. The efficiency of the capacitors also improves at submaximal electric fields when small molecules are included. This work demonstrates the ability to use dilute blended electroactive additives in polymer capacitors to improve key performance metrics while helping to decrease the energy losses that hinder the applicability of capacitors comprising solution-processable engineering polymers such as PC and PMMA. The choice of readily soluble polymer dielectrics and complementary use of simple solution processing offer a scalable, cost-effective method for the production of high-performance polymer capacitors.

  PublisherDOI

• Utilizing pi-peptide supramolecular polymers to template growth of hybrid organic–inorganic electronic materials

  RSC Applied Interfaces · 2024-01-01 · 1 citations

  articleOpen accessSenior authorCorresponding

  We investigated and compared the growth of three different minerals (KCl, CsCl, and CdS) templated by assemblies of perylene diimide (PDI)-based π-peptides with varying amino acid sequences.

  PublisherOA PDFDOI

• Polymeric Semiconductor in Field-Effect Transistors Utilizing Flexible and High-Surface Area Expanded Poly(tetrafluoroethylene) Membrane Gate Dielectrics

  ACS Applied Materials & Interfaces · 2024-03-04 · 2 citations

  articleCorresponding

  Organic field-effect transistors (OFETs) were fabricated using three high-surface area and flexible expanded-poly(tetrafluoroethylene) (ePTFE) membranes in gate dielectrics, along with the semiconducting polymer poly[2,5-bis(2-octyldodecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione-3,6-diyl)-alt-(2,2′:5′,2″:5″,2‴-quaterthiophen-5,5‴-diyl)] (PDPP4T). The transistor behavior of these devices was investigated following annealing at 50, 100, 150, and 200 °C, all sustained for 1 h. For annealing temperatures above 50 °C, the OFETs displayed improved transistor behavior and a significant increase in output current while maintaining similar magnitudes of Vth shifts when subjected to static voltage compared to those kept at ambient temperature. We also tested the response to NO2 gas for further characterization and for possible applications. The ePTFE–PDPP4T interface of each membrane was characterized via scanning electron microscopy for all four annealing temperatures to derive a model for the hole mobility of the ePTFE–PDPP4T OFETs that accounts for the microporous structure of the ePTFE and consequently adjusts the channel width of the OFET. Using this model, a maximum hole mobility of 1.8 ± 1.0 cm2/V s was calculated for the polymer in an ePTFE–PDPP4T OFET annealed at 200 °C, whereas a PDPP4T OFET using only the native silicon wafer oxide as a gate dielectric exhibited a hole mobility of just 0.09 ± 0.03 cm2/V s at the same annealing condition. This work demonstrates that responsive semiconducting polymer films can be deposited on nominally nonwetting and extremely bendable membranes, and the charge carrier mobility can be significantly increased compared to their as-prepared state by using thermally durable polymer membranes with unique microstructures as gate dielectrics.

  PublisherDOI

• Increased Static Charge‐Induced Threshold Voltage Shifts and Memristor Activity in Pentacene OFETs Comprising Polystyrene‐Based Gate Dielectrics Containing Electroactive Small Molecule Crystallites

  Advanced Functional Materials · 2024-09-18 · 5 citations

  articleOpen accessSenior authorCorresponding

  Abstract Top‐contact bottom‐gate pentacene OFETs are fabricated with single layer dielectrics comprised of either polystyrene (PS), poly(4‐methylstyrene) (P4MS), or poly(4‐tert‐butylstyrene) (P4TBS). The polystyrenes are blended with varying concentrations of two different small molecules, dibenzotetrathiafulvalene (DBTTF) and 2,8‐difluoro‐5,11‐bis(triethylsilylethynyl)anthradithiophene (diF‐TES‐ADT), to form small, separated crystallites contained throughout the polymer dielectric layer. The OFET characteristics of these devices are investigated and their threshold voltage shifts are measured after −70 V static charging for 5 min. Two‐terminal measurements are conducted using multiple different gate biases in the range of −50 to +50 V to investigate memristor behavior in the devices. OFETs containing DBTTF exhibited ΔV th increases as large as 330% relative to control OFETs containing no DBTTF, while OFETs containing at least 7.5 wt.% DBTTF exhibited memristor activity, with currents ranging from 20 nA to 44 µA depending on the applied bias. This work demonstrates that including small, separated crystallites in polymer dielectrics enhances their charge storage ability and can be promising for creating nonbinary memory devices for data processing. Additionally, the observed memristor activity indicates the OFETs in this work can be used in development of neuromorphic systems that aim to mimic the synaptic behavior of the human nervous system.

  PublisherOA PDFDOI

Recent grants

• SENSORS: Maximization of Electronic Sensitivity and Selectivity of Organic Semiconductors Through Complexation and Film Architecture

  NSF · $240k · 2005–2008

• EXP-LA: IMPACT (Imprinted Polymer Array for Counterterrorism):

  NSF · $800k · 2007–2011

• P-N Interface Probing and Design for Organic/Hybrid Photovoltaics and Circuit Components

  NSF · $350k · 2008–2012

• Mutual Synthesis of Conjugated Polymers and Dopants for Well-Ordered Self-Assemblies

  NSF · $400k · 2017–2021

• Transistor and Circuit Designs for Real Time Brain Injury Biomarker Detection

  NIH · $427k · 2015–2018

Frequent coauthors

• Andrew J. Lovinger

  48 shared

• M. L. Schilling

  47 shared

• Ananth Dodabalapur

  The University of Texas at Austin

  46 shared

• Wei Shi

  Shanghai University

  42 shared

• Zhenan Bao

  37 shared

• Junsheng Yu

  University of Electronic Science and Technology of China

  33 shared

• Byung Jun Jung

  Samsung (South Korea)

  30 shared

• Josué F. Martínez Hardigree

  University of Oxford

  28 shared

Awards & honors

• National Academy of Inventors (2017)
• two R&D 100 Awards