Organic spontaneous emission approaching the monochromatic limit.

Mamada, Masashi; Kataoka, Kota; Ochi, Junki; Lee, Taehwan; Matsumoto, Ryuji; Yoshioka, Mayu; Fukushima, Daisuke; Hatakeyama, Takuji · Science · 2026

basic_science · Level V

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Abstract

Spontaneous emission is inherently associated with spectral broadening mechanisms, resulting in finite bandwidth in the emitted light. Narrowing this linewidth toward the monochromatic limit has long been a central pursuit in photonics, as it determines the ultimate color purity of nonstimulated light sources. Organic luminescent materials offer facile wavelength tunability but typically exhibit broad emission bands (>40 nanometers). The emergence of multiple-resonance emitters has provided a promising route to overcome this limitation, yet most reported systems remain within 20 to 30 nanometers. We present a molecular design strategy that amplifies the multiple-resonance effect through molecular repetition, yielding fluorescence with linewidths of 6.9 nanometers in toluene, 5.5 nanometers in 3-methylpentane, and 9.1 nanometers in a doped polymer film, placing this molecular framework among the narrowest-band organic luminophores reported.