# Research at Mei Group

**Mei group’s** research asks one question at successively larger scales: how far can a functional polymer be pushed, and what becomes possible when it is? Over ten years the answers have moved from organic semiconductors that keep working at 220 °C, to a conducting polymer that combines metal-like conductivity with air stability and solution processing (n-PBDF), to devices in which light directly programs the ionic and electronic state of the material, and now to electronic materials that grow inside living tissue and modulate the nervous system. Along the way the same chemistry has reached the market through roll-to-roll electrochromic films. Our work is organised along four stages that build on each other:

- **Breaking material limits.** Organic semiconductors that push beyond commonly assumed limits in operating temperature and performance.

- **Reconstructing polymerisation.** n-PBDF and polymerisation-driven self-assembly: polymerisation, doping and ordering coupled in one step.

- **Connecting with living systems.** From light-programmed organic synapses to living electronics grown in vivo and adaptive neurotherapy.

- **Translating to industry.** Flexible electrochromics from the laboratory to global production lines (Ambilight).

## Living Electronics

**Organic Bio-electronics** are a generic platform with unprecedented biological recording and regulation potentials - a technology that bridges biology with electronics. It is based on a unique combination of both electronic and ionic conductivity presented by conducting and semiconducting polymers that enables a means to effectively interface biology with conventional electronics. In our group, we design and synthesize such electronic and ionic polymers, integrate them into organic electrochemical transistors (OECTs), and use these devices to interrogate interesting biological processes such as neural activities, as well as disease diagnosis and monitoring.

### Living Electronics: Conducting Polymers Grown In Vivo

Conventional bioelectronic devices are fabricated outside the body and then connected to tissue by implantation or other means. Living electronics takes a different approach: the electronic material grows in situ inside the living body and merges naturally with the nervous system. A reaction catalysed by endogenous heme proteins in the blood forms a conducting n-PBDF polymer network directly in living tissue, fusing material and tissue together. Combined with near-infrared light stimulation, the material’s photothermal response provides millisecond-scale, reversible suppression of neural excitability in mice, without rigid implants or genetic modification. The goal is long-term, precise, bidirectional integration with and modulation of the living nervous system. This direction is the focus of the center’s first stage, which aims to reveal the relationships between material formation, electron and ion transport, tissue-interface properties and biological response.

![Schematic from the group's 2026 Science paper: haemoglobin and the monomer BDF injected into the mouse brain grow from oligomers into an n-PBDF polymer network around the neurons, beside a recording trace in which the firing stops during a pulse of light](https://www.jianguomei.com/_astro/05-living-electronics-conducting-polymers-grown-in-vivo-card.BFsmPDEx_1w1e0p.webp)

Haemoglobin and the monomer BDF, injected into the mouse brain, polymerise around the neurons into a conducting n-PBDF network, and the recorded neural activity falls silent while the light is on.

#### Representative Publications

- [Blood-catalyzed n-doped polymers for reversible optical neural control](https://www.jianguomei.com/en/publications/#pub-146)Science **2026**, *392*, eadu5500.

### Programming Neural Function with Light, Ions and Electrons

A conventional photodetector can “see” light, but it cannot do what a biological synapse does: let light directly change the strength of a synaptic connection and form a memory. We established a light-ion-electron coupling mechanism that uses light to regulate electrochemical doping, achieving multi-level, non-volatile programming of the electronic state of organic materials. The result is organic optoelectronic synapses that combine perception, processing and memory. Light no longer only generates a current; it directly programs the ionic-electronic state of the material. Building on this, CLEAN will investigate whether a verifiable mechanistic link exists between the dynamic response of artificial materials and the plasticity of biological neurons, testing each hypothesis step by step through electrophysiology, optical imaging and behavioural experiments.

![Schematic from the group's 2026 Science paper: neurons wrapped in the soft, tissue-like n-PBDF electrode stop firing while near-infrared light is on and fire again afterwards](https://www.jianguomei.com/_astro/06-programming-neural-function-with-light-ions-and-electrons-card.dlJHfW1f_Klhb7.webp)

Light reprograms neural function: neurons wrapped in the soft n-PBDF electrode fall silent while near-infrared light is on and fire again once it is off.

#### Representative Publications

- [Organic optoelectronic synapse based on photon-modulated electrochemical doping](https://www.jianguomei.com/en/publications/#pub-117)Nat. Photonics **2023**, *17*, 629-637.

### Adaptive Neuroelectronics and Neurotherapy

The nervous system changes dynamically and adapts continuously; stimulation or intervention with fixed parameters cannot fully capture changes in a complex neural state. The goal of adaptive neuroelectronics is, on the basis of reliable signal acquisition and mechanistic understanding, to connect neural activity monitoring, state recognition, modulation strategy and feedback validation into a research system that can adjust its intervention to the physiological state. Drawing on the Second Affiliated Hospital, Zhejiang University School of Medicine and its medical research platforms, we are building a chain of evidence from the mechanism of material action and changes in cell function to effects on neural circuits and behaviour, together with procedures for evaluating biocompatibility, tissue response, long-term stability and the effect of neural intervention. Initial research focuses on scenarios with measurable electrophysiological markers, such as epilepsy-related abnormal neural activity; the feasibility of extending it to Parkinson’s disease and other models of neural dysfunction is then evaluated step by step, according to the earlier mechanistic research and the capabilities of the platforms. Functional improvement in disease models is a research goal to be verified by experiment; its clinical efficacy is not presumed.

![Schematic from a 2021 Matter paper co-authored by the group: near-infrared light acting through photoacoustic nanotransducers on a neuron evokes an action potential that travels on to the next neuron; below, a mouse brain with recording electrodes](https://www.jianguomei.com/_astro/07-adaptive-neuroelectronics-and-neurotherapy-card.CxZykM0N_Z195ILR.webp)

Photoacoustic nanotransducers turn near-infrared light into a local acoustic stimulus that evokes action potentials, in cultured neurons and in the mouse brain.

### Neuromorphic Intelligent Sensing

A neuromorphic intelligent sensing system brings sensing, computing and storage together in one organic device, aiming at low power and high efficiency. Building on mixed ionic-electronic conductors and optoelectronic functional materials, we build hemispherical retinas and brain-inspired vision systems and explore their potential in neuromorphic sensing, intelligent sensing, and related information processing, toward applications such as brain-machine interfaces and brain-inspired vision. At CLEAN this is an extension of the center’s materials and device research capabilities, not a core task of the initial neuromodulation program.

![Schematic from the group's 2023 Nature Photonics paper: an organic optoelectronic synapse in which a beam of light drives anion and cation flow between the electrodes](https://www.jianguomei.com/_astro/08-neuromorphic-intelligent-sensing-card.DyxSzk95_1As71X.webp)

Sensing, computing and storing in one device: in an organic optoelectronic synapse, light drives ions between the electrodes and the device keeps the change as memory.

## Electrochromics

![A pair of electrochromic sunglasses changing the level of dark vs transparent as the pages scroll, laying on a concrete ledge in front of a fountain.](https://www.jianguomei.com/_astro/02-electrochromics-banner.RNoZMm3F_101lWd.png)

**Electrochromic** polymers are conjugated polymers that reversibly modulate light and heat transmission in response to an applied voltage, and they can be laminated into glass for energy saving and visual comfort. The major obstacles to the market adoption of current electrochromic technologies are (1) premium pricing, (2) the lag in response time between the colored and the bleached states, and (3) the lack of color neutrality (a neutral grey color). In addition, current electrochromic technologies are incapable of turning the millions of existing static windows into dynamic, switchable windows. By applying an adhesive layer to roll-to-roll manufactured thin-film electrochromic foils, which can then be laminated onto flat or curved glass, we investigate an electrochromic technology that is scalable and cost-effective and that fulfills unmet needs in the switchable glass industry. We currently focus on the scale-up synthesis of electrochromic polymers and the roll-to-roll fabrication of electrochromic devices in partnership with industrial experts. To this end, Dr. Mei co-founded [Ambilight Inc](https://ambilightinc.com/), a company that brings electrochromic technologies to market.

### Anodically coloring electrochromic polymers (ACEs)

Most electrochromic polymers switch from a colored state to a more transmissive one, but they never become fully clear: residual absorption in the visible range limits their optical contrast. We introduced a molecular design that places meta-conjugated linkers (MCLs) between aromatic units along the polymer backbone. The linkers interrupt charge delocalization and widen the band gap of the neutral polymer, so that it transmits nearly 100% of visible light, while the aromatic units keep the oxidation potential low, so that the film switches stably to a deep color when it is oxidized. The resulting polymers offer a wide choice of colors, an optical contrast above 93% and less than 3% contrast decay over 5,000 cycles ([JACS Au, 2024](https://dx.doi.org/10.1021/jacsau.4c00254)), bringing transparent-to-colored switching within reach of practical devices for visual comfort and energy saving.

![Absorbance spectrum, the polymer repeat unit of meta-conjugated linkers and aromatic units, and photographs and device diagrams of an electrochromic film switching from transparent to black](https://www.jianguomei.com/_astro/09-transparent-to-colored-electrochromic-polymers.D3No8i87_rL3H3.webp)

A meta-conjugated electrochromic polymer switches between a nearly colorless neutral state and a black oxidized state.

#### Representative Publications

- [Transparent Electrochromic Polymers with High Optical Contrast and Contrast Ratio](https://www.jianguomei.com/en/publications/#pub-128)JACS Au **2024**, *4*, 2291-2299.

### Flexible Electrochromics and Technology Translation

Electrochromic technology has promised low-power dynamic tinting for decades, but cost, uniformity, switching speed and lifetime kept large-area devices stuck in the laboratory. [Ambilight](https://ambilightinc.com/), co-founded by Prof. Mei in 2017, developed high-performance electrochromic polymers together with a roll-to-roll process that produces electrochromic films continuously over large areas, and used them to carry the technology from fundamental research through engineering to mass manufacturing, now found in cars, buildings and consumer electronics. The company has raised several hundred million US dollars and been recognised as a “little giant,” a high-tech enterprise, and a unicorn.

![Technicians handling a large electrochromic film on a roll-to-roll line](https://www.jianguomei.com/_astro/04-flexible-electrochromics-and-technology-translation.DclfxpWE_Zd13oU.webp)

Roll-to-roll production of electrochromic films at Ambilight.

## Self-Driving Laboratory

![A collaborative robotic system coordinating among reaction modules in the self-driving laboratory.](https://www.jianguomei.com/_astro/03-automation-banner.CZMVux5P_i2J6b.webp)

**Machine-learning Assisted High-throughput Automated Synthesis** combines machine-learning algorithms with automated chemical synthesis to accelerate the discovery and development of new materials. The approach involves using large-scale, parallel chemical reactors to carry out chemical reactions in a high-throughput manner. Machine learning algorithms are then used to analyze the data generated by the high-throughput synthesis process, including information on reaction yield, purity, and other key metrics, to identify patterns and optimize reaction conditions in real time. By leveraging the power of machine learning, researchers can quickly screen a large number of potential reaction conditions, identify the most promising candidates, and rapidly iterate to optimize the synthesis of target compounds. The use of machine learning in high-throughput automated synthesis is used in the Mei group to accelerate the discovery and optimization of new materials with desired properties. We are increasingly letting large language models and autonomous agents plan, run and analyse experiments, so that the design, synthesis and test loop for new electronic and ionic polymers closes faster than a human can turn it.

## Molecular Engineering

![Cover art showing a conjugated polymer chain beside stacked transparent semiconductor layers and an electrode.](https://www.jianguomei.com/_astro/04-molecular-engineering-banner.DlaeH3Zz_ax97H.webp)

**Organic Synthesis** is a key element in our research. We explore new synthetic approaches to prepare new organic materials including conjugated small molecules and polymers, new polymerisation methods and polymer processing. The performance of n-PBDF, our n-doped transparent organic conductor (n-TOC), rivals indium-tin-oxide (ITO), commonly used in phone screens, displays, and solar cells. In other words, n-PBDF can be inside your phones in the future.

**n-PBDF and Polymerisation-Driven Self-Assembly** take this further. n-type conducting polymers have long been held back by low conductivity, instability in air and doping that destroys structural order. n-PBDF, discovered independently in our group, is the first to combine metal-level conductivity, air stability, solution processability and visible-light transparency above 80 %. Around it we have built a scalable synthesis, an understanding of its doping mechanism and ways to control its structure, and we discovered polymerisation-driven spontaneous assembly (PSA), in which polymerisation, doping and ordering are coupled in a single step. Doping no longer breaks order; it drives it. The material is a platform for opto-electric (transparent electrodes replacing ITO), electro-chemical (electrochemical transistors, electrochromics), photo-thermal (smart windows, transparent heaters) and thermo-electric (flexible solid-state cooling) devices, and it is the material that living electronics grows in vivo.

**Materials Characterization and Processing** are also critical components in our research efforts. The essential goal is to establish the relationship among chemical structures-materials processing - thin-film morphologies - functional properties (e.g. mechanical, optical, and electronic properties): our characterisation couples electrical, spectroscopic and morphological measurement to understand how structure sets function.

**Device Fabrication and Integration** are indispensable when it comes to demonstrating the potential of our materials. There are three primary electronic devices we build in the laboratory, including organic field-effect transistors (OEFTs), organic electrochromic (OECDs), and organic electrochemical transistors (OECTs). One example is our high-temperature electronics. Electronic devices normally lose their function as the temperature rises. We proposed and systematically developed high-temperature organic semiconductors as a research direction, uncovered the mechanisms that govern charge transport and structural stability under heat, and, through polymer blending, realised all-plastic organic transistors that operate stably at 220 °C (***Science***, 2018, 362, 1131-1134). This takes organic electronics from room-temperature applications into extreme environments such as engines, spacecraft and downhole sensing.

![Figure 1: microscopy images and size distributions of n-PBDF nanoribbons, high-resolution transmission electron microscopy showing 0.34 nm spacing, and a model of extended chains with hydrogen-bonded duplexes.](https://www.jianguomei.com/_astro/01-n-pbdf-and-polymerisation-driven-self-assembly.CogabXpk_Z1uLkUV.webp)

Long-range extended chains arising from polymerization-driven spontaneous assembly.

> "In our lives, we're constantly taking risks and changing our lifestyles, and discovering new things by trial and error. If you're not making a few mistakes, you're probably not doing very much. Only by taking risks do you make progress"

Arnold Beckman

> "The desire that guides me in all I do is the desire to harness the forces of nature to the service of mankind."

Nikola Tesla