About

Alberto Salleo is the Hong Seh and Vivian W. M. Lim Professor of Photon Science and Senior Fellow at the Precourt Institute for Energy at Stanford University. His research focuses on materials science and engineering, particularly in the areas related to photon science and energy. As a faculty member at Stanford, he contributes to advancing knowledge in these fields through his academic and research activities.

Research topics

• Computer Science
• Artificial Intelligence
• Materials science
• Nanotechnology
• Electrical engineering
• Chemistry
• Engineering
• Optoelectronics
• Computer architecture
• Physics
• Distributed computing
• Embedded system
• Chemical physics
• Biology
• Organic chemistry
• Computer hardware
• Neuroscience
• Chemical engineering
• Optics
• Operating system
• Metallurgy
• Engineering physics
• Electronic engineering
• Physical chemistry

Selected publications

• Optimizing the open-circuit voltage and overall performance for indoor organic photovoltaics via wide-gap polymeric donor materials

  Organic Electronics · 2026-02-24

  article
  PublisherDOI

• Solution-state nanoconfined aggregation and microstructure evolution in blends of conjugated polymers and elastomers

  Proceedings of the National Academy of Sciences · 2026-04-24

  articleOpen access

  Emerging wearable health monitoring technologies require conformable and stretchable devices. Polymer semiconductors composed of π-conjugated polymer aggregates in an elastomeric matrix are remarkable in their ability to provide both high stretchability and enhanced charge transport. Understanding their film formation process is critical in improving charge transport, imparting added functionalities, and advancing large-scale production of high-performing polymer electronic devices. Here, using a poly-thieno[3,2-b]thiophene-diketopyrrolopyrrole (DPPTT): polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (SEBS) blend as a model system, electron tomography of the blend reveals the presence of bundles of conjugated polymer nanofibers spanning the thickness of the films. High-resolution cryogenic electron microscopy (cryo-EM) of solution and thin films reveals that the nanoconfined DPPTT nanofibers in blends are composed of the aligned DPPTT 1D aggregates present in solution. In contrast, neat DPPTT solutions and thin films contain irregular crystalline domains with random orientations. In situ grazing incidence wide-angle X-ray scattering (GIWAXS) studies reveal that DPPTT crystallization commences earlier in blends compared to neat films. Combining observations from both in situ ultraviolet-visible spectroscopy, in situ GIWAXS and cryo-EM reveal that 1D aggregates in blend solution bundle and align into interconnected larger fibers that are nanoconfined in the SEBS matrix. This morphology is desirable for efficient charge transport and good mechanical strength. In contrast, neat DPPTT films contain randomly oriented smaller aggregates with an increased fraction of disordered domains. Overall, our work provides critical insights on the impact of solution composition and processing conditions on thin film morphology for achieving multifunctional high-performing electronic polymer composites.

  PublisherDOI

• pH Controls Charge Localization in Redox-Active Ladder Polymers

  Journal of the American Chemical Society · 2026-02-25

  article

  Organic mixed ionic-electronic conducting polymers (OMIECs) are versatile active materials for applications in transistors, energy storage, and bioelectronics. To meet the varied demands of these technologies, the chemical structure of an OMIEC is often designed with the goal of modifying the localization of added charge, modulating the energetics of frontier orbitals, and altering the degree of charge transfer to charge compensating species. Here, we show that the redox behavior of the archetypal ladder OMIEC, poly(benzimidazobenzophenanthroline) (BBL), is fundamentally modulated by the pH of the electrolyte, even under neutral to basic conditions where protons were previously assumed to not participate in redox processes. Through a combination of electrochemical characterization, operando Raman spectroscopy, ab initio simulations and electrochemical modeling with a multicomponent regular solution framework, we untangle BBL's redox mechanism. Our results reveal the competitive formation of proton-coupled and salt cation-coupled redox states, each possessing distinct characteristics. Notably, we find that proton-coupled redox dominates at neutral pHs, challenging the prevailing view that BBL is reduced to its salt-compensated bipolaronic form in this pH regime. Using a modified Pourbaix diagram, we illustrate how the balance between a proton-coupled and salt cation-coupled form of BBL can be continuously tuned via pH and applied potential. These findings highlight the complexity of multiphase coexistence and nontrivial effect of pH in controlling the redox properties of n-type ladder OMIECs, paving the way to understand and ultimately control a wide range of aqueous electrochemical reactions.

  PublisherDOI

• Cation–polymer interactions drive water expulsion and deswelling in n-type ladder organic mixed conductors

  Open Access CRIS of the University of Bern · 2026-01-01

  articleOpen access
  PublisherDOI

• Knowledge gaps for neuromorphic ionic computing

  Science · 2026-05-07

  article

  Neuromorphic ionic computing is inspired by the brain's use of ions for ultralow-energy computation-its massive parallelism, adaptability, and learning capabilities. This emerging paradigm can overcome limitations of conventional silicon-based computing by enabling colocated memory and processing, multicarrier information streams, and massive three-dimensional connectivity. However, substantial knowledge gaps remain in understanding and engineering ionic transport, energy dissipation, materials design, and scalable device architectures. This Review explores these critical challenges across seven key domains, highlighting the need for new theoretical approaches, materials, device concepts, and fabrication strategies. We argue that advancing ionic neuromorphic systems requires an interdisciplinary approach, integrating insights from biology and neuroscience, nanofluidics, materials science, and systems engineering to enable a new class of energy-efficient, robust, and reconfigurable computing technologies.

  PublisherDOI

• Revealing the Full Potential of Glycolated Mixed Ionic-Electronic Semiconductors – Symmetric Monomer Polymerization to Boost Electrochemical Transistor Performance

  University of Birmingham Research Portal (University of Birmingham) · 2026-02-12

  article
  Publisher

• Cation-polymer interactions drive water expulsion and deswelling in n-type ladder organic mixed conductors.

  Open Access CRIS of the University of Bern · 2026-02-17

  articleOpen access

  Controlling ion-polymer interactions in organic mixed ionic-electronic conductors is crucial for optimizing device performance in applications ranging from bioelectronics and energy storage to photonics. Achieving this requires a molecular-level understanding of how ion uptake, solvation and polymer structure evolve during electrochemical doping. Here using a multimodal operando approach, we uncover an unexpected response in the prototypical n-type ladder polymer poly(benzimidazobenzophenanthroline) (BBL) on doping with protic cations such as ammonium. At high doping levels, strong ion-polymer interactions (primarily hydrogen bonding) between cations and the BBL backbone promote charge localization and disrupt ion hydration, leading to a pronounced reduction in mass and thickness. Operando 2H NMR identifies water expulsion, rather than ion removal, as the origin of this deswelling. Our combined experimental and modelling results reveal a previously unobserved regime of ion-polymer coupling in organic mixed ionic-electronic conductors, establishing a framework for material design and applications that span (bio-)electronics to photonics.

  PublisherDOI

• Additive-Induced Morphology Change of Polymer Film Enables Enhanced Charge Mobility and Faster Organic Electrochemical Transistor Switching

  ACS Applied Polymer Materials · 2026-01-19

  articleOpen access

  Conjugated polymers (CPs) play an important role in organic electrochemical transistors (OECTs) for bioelectronics and related applications, where they serve as channel materials. Currently, most successful polymers for CPs are re-engineered from traditional CPs by replacing hydrophobic alkyl side chains with hydrophilic ethylene glycol or ionic groups. Frustratingly, the enhanced ion transport often compromises the charge mobility of the original CP. In this work, we present an additive-mediated method to construct a modified poly-(3-hexylthiophene) (P3HT) film to enable efficient ion migration. The additive is designed with a cleavable diazo group that releases nitrogen and 2-methoxyethanol, a volatile compound, to alter the P3HT film morphology. OECTs based on the film exhibit improved response times. Interestingly, the process also enhances the crystallinity of P3HT, leading to higher hole mobility compared with pristine P3HT. This study proposes an in situ strategy to achieve the functionality of the OMIEC via morphological regulation, offering a promising route to simultaneously enhance both ion accessibility and charge mobility.

  PublisherDOI

• Side Chains Override Crystallinity in n‐Type Organic Mixed Conductors

  Advanced Materials · 2026-04-29

  article

  In organic semiconductors, crystallinity is commonly associated with enhanced charge transport. For organic mixed ionic-electronic conductors (OMIECs), materials at the core of bioelectronic devices, whether higher crystallinity consistently translates into improved performance remains unresolved. Here, we use thermal annealing to control the crystallinity of three electron-transporting OMIECs bearing either branched or linear ethylene glycol side chains that are used to promote ion transport. Although annealing uniformly enhances crystallinity across all materials, it improves mixed charge transport only in polymers with linear side chains by doubling electronic charge mobility. Specifically, annealed films with branched side chains exhibit reduced mobility and low water uptake, coinciding with a pronounced bipolaron formation, which we uncovered using a combination of in-operando physicochemical characterization methods. Thermal annealing is also used to sterilize these materials for interfacing with living cells, with the benefit of improved sensor performance. These results reveal that crystallinity can hinder mixed conductivity depending on side-chain architecture, independent of the backbone chemistry. By challenging the prevailing assumption that crystallinity is universally beneficial for charge transport, this work establishes design rules for developing OMIECs that combine high performance with compatibility for fabrication and sterilization processes involving high temperatures, paving the way for reliable, scalable bioelectronic devices.

  PublisherDOI

• Reproducible High‐Impedance Supported Lipid Bilayers on PEDOT:PSS

  Apollo (University of Cambridge) · 2026-03-31

  articleOpen accessSenior author

  ABSTRACT Supported lipid bilayer (SLB) sensing platforms are a promising, versatile technology for studying native cell membrane processes and enabling applications harnessing them. Forming SLBs on conductive polymers such as poly(3,4‐ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) allows the use of electrochemical impedance spectroscopy (EIS) as a rapid, sensitive technique to probe dynamic membrane interactions. However, since these biosensors require large impedances to measure biological signals, their applicability is limited by difficulties in reproducing high‐impedance bilayers. This challenge is compounded by the need to controllably functionalize the electrode using hydrophilic treatments (e.g., oxygen plasma). This study develops a protocol for reproducible high‐impedance bilayers by investigating how oxygen plasma‐treating PEDOT:PSS influences SLB formation. Excessive plasma treatment is shown to hinder SLB formation by creating an unstable PEDOT:PSS surface in water. By controlling parameters affecting SLB formation, resistances of up to 5.9 kΩ cm 2 for 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) and 31 kΩ cm 2 for a 4:1 mixture of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine (DOPC) and 1,2‐dioleoyl‐3‐trimethylammonium‐propane (DOTAP) SLBs are achieved. At least one electrode per chip exceeds 25 and 1000 Ω cm 2 with corresponding surface coverages of 96% and 99.9% for these lipid compositions, respectively, demonstrating a 100% yield of chips and highlighting the protocol's potential for advancing SLB‐based biosensors.

  PublisherOA PDFDOI

Recent grants

• Engineered Grain Boundaries and their Properties in Crystalline Organic Semiconductors

  NSF · $380k · 2012–2015

• Materials World Network: The Ideal Nanowire Transistor-Materials Development for Contact-Doped ZnO nanowires

  NSF · $431k · 2010–2015

• Structure-property relationships in novel conjugated mixed conductors

  NSF · $416k · 2018–2022

• Molecularly selective sensors based on organic semiconductors and artificial receptors: demonstrations and scaling studies

  NSF · $300k · 2018–2021

• E2CDA: Type II: A new non-volatile electrochemical transistor as an artificial synapse: device scaling studies

  NSF · $210k · 2017–2020

Frequent coauthors

• Iain McCulloch

  University of Oxford

  153 shared

• Alexander Giovannitti

  Stanford University

  80 shared

• Michael F. Toney

  68 shared

• Jonathan Rivnay

  Materials Science & Engineering

  59 shared

• Koen Vandewal

  Hasselt University

  45 shared

• Martin Heeney

  40 shared

• Michael D. McGehee

  University of Colorado Boulder

  40 shared

• Michael L. Chabinyc

  University of California, Santa Barbara

  39 shared

Education

• Ph.D., Materials Science and Engineering

  Stanford University

  2001

• M.S., Materials Science and Engineering

  Stanford University

  1997

• B.S., Physics

  University of California, Santa Barbara

  1994