Next-generation LEDs and solar cells powered by new spinel-type sulfide semiconductor

Next-generation LEDs and solar cells powered by new spinel-type sulfide semiconductor
by Riko Seibo
Tokyo, Japan (SPX) Oct 06, 2025

A new spinel-type sulfide semiconductor capable of emitting light from violet to orange at room temperature could pave the way for advanced LEDs and solar cells, according to researchers from the Institute of Science Tokyo. The compound, (Zn,Mg)Sc2S4, can be chemically tuned to exhibit either n-type or p-type conduction, enabling pn homojunction devices that integrate light emission and absorption functions in a single material.

The research team, led by Professor Hidenori Hiramatsu and Associate Professor Kota Hanzawa from Science Tokyo's Materials and Structures Laboratory, along with Distinguished Professor Hideo Hosono of the MDX Research Center for Element Strategy, reported the discovery in the Journal of the American Chemical Society on September 17, 2025.

LEDs, solar cells, and semiconductor lasers rely on pn junctions, where electrons and holes either recombine to emit light or separate to generate current. The team's new material demonstrates strong potential for both applications, overcoming efficiency gaps that have limited current devices based on gallium arsenide and silicon.

"Our semiconductor material is suitable for both green emission and photovoltaic applications," said Hiramatsu, addressing the persistent "green gap" problem that has challenged LED technology for decades.

The compound's spinel structure (AB2S4) contributes to its unique optoelectronic behavior: the A-site cations like zinc provide an s-orbital-derived conduction band minimum, while the B-site scandium cations with anisotropic d0 orbitals stabilize the direct bandgap by suppressing competing valence states.

Undoped ZnSc2S4 emits a bright orange glow, while magnesium substitution shifts emission toward green and blue. Substituting titanium for scandium or reducing zinc content allows controlled switching between n-type and p-type conduction, with conductivity spanning nine orders of magnitude - from insulating (2.5 + 10-11 S/cm) to semiconducting (1.8 + 10-2 S/cm).

"The sulfide semiconductor identified in this study meets the requirements for both highly efficient light absorbers in solar cells and green light emitters in LEDs, making it a strong candidate for next-generation optoelectronic devices," Hiramatsu added.

Research Report:d0 Cation-Based Spinel-Type Sulfide Semiconductors with Color-Tunable Direct-Gap and Ambipolar Dopability