#dopants

IRAA doping could reshape organic semiconductors with cleaner, faster charge control

Semiconductors are an indispensable part of modern-day technologies ranging from computers and smartphones to solar panels and LED lighting. Their ability to control the flow of electrical charge makes them essential for how devices generate, process, and use energy. In renewable energy technologies such as solar cells, semiconductor performance directly determines how efficiently sunlight can be converted into electricity. Conventional semiconductor materials are mostly silicon-based, while new age semiconductors (such as perovskite-based and organic semiconductors) address the challenges associated with conventional silicon-based semiconductors.

Surprising twist: Chirality in polymers enhances conductivity after doping

A new study marks a significant step forward in positioning synthetic polymers as an alternative to expensive, unsustainable minerals used in the manufacture of devices such as conductors, transistors and diodes. These newly tweaked polymers—developed by University of Illinois Urbana-Champaign professors Ying Diao and Joaquín Rodríguez López in collaboration with Jean-Luc Brédas of the University of Arizona, John Reynolds of Georgia Tech and Dali Sun of North Carolina State University—possess special properties enabled by controlled chirality and chemical doping. The study findings are published in the journal Nature Communications. Understanding chirality and doping in polymers Chirality, which can arise from persistent twisting of a polymer's backbone, is one of nature's strategies for building complexity. One advantage of chirality is that it allows materials to efficiently funnel electricity by transporting electrons with the same spin direction—or quantum state.

Concentration‑controlled doping turns a p‑type polymer semiconductor into its n‑type counterpart

A South Korean research team has, for the first time, uncovered the molecular-level mechanism by which trace amounts of impurities—known as dopants—can reverse charge polarity in organic polymer semiconductors. A joint research team led by Professor Kilwon Cho, Ph.D. candidates Eunsol Ok and Sein Chung from the Department of Chemical Engineering at POSTECH, and Professor Boseok Kang from the Department of Nano Engineering at Sungkyunkwan University (SKKU), has revealed at the molecular level how adjusting the concentration of a single dopant enables polymer semiconductors to switch between positive (p-type) and negative (n-type) conduction. Their findings were recently published in the journal, Advanced Materials.

Advancing semiconductor thermoelectrics via thickness doping

Thermoelectricity is capable of direct energy conversion between heat and electricity, promising low-grade heat harvesting and solid-state cooling for the transition to sustainable electronics. Currently, bulk Bi2Te3 polycrystalline undergoes a composite synthesis process that typically encompasses melting, ball milling, hot pressing, and spark plasma sintering, aiming to introduce a myriad of structural defects for enhanced performance. Conversely, the synthesis procedure of thin films is constrained by physical thickness and substrate compatibility, where singular deposition methodologies with performance enhancement are largely reliant on post-deposition annealing treatment.

Targeted doping strategy use copper ions to boost thermoelectric performance

QUT researchers have identified a new method for incorporating copper ions into a germanium telluride thermoelectric material that significantly improves its ability to convert waste heat into electricity. Germanium telluride is used in electronic devices to turn heat into electricity, helping save energy and power small devices. In a study published in Nature Communications, the researchers detail the targeted "copper doping" strategy using copper ions. Alongside first author Yongqi Chen, the QUT researchers contributing to the study include Professor Zhi-Gang Chen, Dr. Meng Li, Dr. Xiaodong Wang, and others.

Lanthanide-doped nanomaterials unlock new horizons for advanced imaging and photonics

Researchers from the National University of Singapore (NUS) have developed a new class of lanthanide-doped nanomaterials that exhibit extraordinarily high optical nonlinearity, exceeding a magnitude of 500. This achievement establishes a new global benchmark for photon avalanche nanophotonics. The paper is published in Nature. Photon avalanche is an exceptionally rare and powerful photophysical effect characterized by its nonlinear response to light excitation. In conventional fluorescence, the intensity of emitted light typically increases proportionally to the excitation intensity, reflecting a linear input-output relationship. However, photon avalanche systems display an abrupt, nonlinear behavior: once the excitation intensity surpasses a critical threshold, even a minor increase leads to a sudden, exponential surge in emission output.

Sources of Color: Doped semiconductors

The mechanism that creates color in doped or activated semiconductors is much the same as that in pure semiconductors—energy bands and the resulting size of the band gap determine the resulting color. However, the difference is that the color is no longer a fundamental aspect of the material itself, but a result of impurities. Light emitting diodes (LEDs) are almost always the result of doped semiconductors, with materials mixed in different quantities to get the desired colors. (Gallium, arsenic, and phosphorus are common dopants/elements.) The color of yellow and blue diamond are caused by similar impurity/dopant atoms.

Sources/Further Reading: (WebExhibits) (University of Wisconsin) (American Mineralogist) (Electronics Tutorials)

Scandium-doped TiO₂ boosts photocatalytic water splitting efficiency

Photocatalytic water splitting is a clean energy technology that uses sunlight to split water into oxygen and hydrogen in order to produce green hydrogen—a clean fuel—without relying on fossil fuels. The process is driven by a photocatalyst. While titanium dioxide (TiO2) has long been studied as a promising semiconductor for photocatalytic water splitting, its efficiency has been hindered by rapid charge recombination and insufficient charge separation. Now, however, a research team led by Prof. Liu Gang from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences (CAS) has achieved a breakthrough in photocatalytic water splitting by developing a scandium (Sc)-doped titanium dioxide (TiO2) semiconductor in the rutile crystal phase. The study is published in the Journal of the American Chemical Society.