2000 Nobel Prize in Chemistry
Reason for Award
for the discovery and development of conductive polymers
Laureates
United States of America
United States of America, 
New Zealand
Japan
Explanation
We usually learn that plastic does not conduct electricity. Dr. Heeger and his colleagues found a special way to let electricity flow through certain plastics. Picture beads on a string: when an empty spot appears, the beads hop along the chain, just like electric charges move. Conductive plastic can become bendable wires or glowing sheets. It may make our TVs and phone screens thinner and lighter. That is why this discovery is an exciting step toward a brighter everyday life.
Related Keywords
conductive polymers
Conductive polymers are plastics given pathways that allow electrons to move. They keep the light weight, flexibility, and easy processing of ordinary polymers while reaching metal-like conductivities. Doping permits precise control of carrier density, allowing states from semiconducting to metallic. Transparent electrodes and organic LEDs are fast-growing applications that can replace inorganic materials. Low-energy solution processing and compatibility with ink-jet printing offer additional environmental and manufacturing benefits.
doping
Doping introduces charge carriers by oxidizing (p-doping) or reducing (n-doping) the polymer backbone. Iodine, AsF₅, and alkali metals are typical dopants. Carrier injection narrows the band gap and boosts conductivity exponentially. Reversible electrochemical doping allows the material to be switched ON and OFF like an electronic valve. This reversibility underpins electrochromic devices and polymer-based energy-storage systems.
polyacetylene
Polyacetylene is a one-dimensional conjugated polymer obtained by polymerizing acetylene (CH≡CH) and exists in cis and trans crystalline phases. Undoped, it is a semiconductor, yet iodine or AsF₅ doping yields conductivities of ~10³ S cm⁻¹. The Peierls-induced band gap that collapses upon doping was pivotal to the field. The material served as an experimental platform for testing polaron and soliton physics. Although now often replaced for safety and processing reasons, its historical impact remains substantial.
π-conjugated system
A π-conjugated system is a backbone in which single and double bonds alternate, allowing π electrons to delocalize across the molecule. This delocalization raises electron freedom and permits band formation. In long polymer chains, the bands become quasi-continuous, giving semiconductor-like behavior. When doping introduces carriers near the Fermi level, metallic conduction emerges. π-Conjugation also underlies optical absorption, emission, and thermoelectric properties.
polaron
A polaron is a quasi-particle in which a charge carrier (electron or hole) couples with local lattice distortion within a conductive polymer. The resulting complex behaves as a unified entity with modified bond lengths around it. Polarons carry spin 1/2 and charge ±e and are often detected via ESR. As the electron moves, the accompanying distortion follows, giving a higher effective mass yet retaining considerable mobility. At high doping levels, polarons pair to form solitons or bipolarons, altering the transport mechanism.
soliton
A soliton is a phase defect in a one-dimensional conjugated polymer; in polyacetylene it appears when the sequence of double bonds shifts. Various charge–spin combinations are predicted, such as neutral spin-1/2 or charged spin-0 types. A soliton can travel along the chain while preserving its shape, transmitting information or energy without dissipation. It creates new absorption peaks and nonlinear optical responses. Because it influences both conductivity and optical behavior, the soliton concept is vital for device design.
organic electronics
Organic electronics is the field of electronic devices built from carbon-based semiconductors and conductive polymers. Organic LED displays, flexible solar cells, and organic transistors are prominent examples. They allow low-temperature, low-cost, large-area fabrication and can be printed, differentiating them from silicon circuits. The flexibility to bend or fold while operating suits wearable gadgets. Their biocompatibility and degradability are fueling applications in medical sensing and environmental monitoring.
electroluminescence
Electroluminescence is the emission of light when electrons and holes recombine inside a material under an applied voltage. In organic LEDs, a conductive polymer acts as an electrode layer and a π-conjugated polymer forms the emissive layer. The emission wavelength can be tuned by molecular design, covering infrared to ultraviolet. Compared with incandescent bulbs, organic LEDs are more efficient and generate less heat, enabling thin and lightweight displays. Fabrication on flexible substrates allows foldable TVs and roll-up lighting now nearing commercialization.