High‐Temperature Afterglow Color Tuning via Förster Resonance Energy Transfer

Why It Matters

The ability to maintain bright afterglow at elevated temperatures while dynamically tuning color opens new possibilities for high‑temperature security tags and temperature‑responsive sensors, expanding the market for organic‑inorganic luminescent devices.

Key Takeaways

• Low-temp boric acid matrix yields stable high-temp afterglow
• TPBA phosphorescence lasts 2.56 s at 460 K
• Rhodamine 6G enables red emission via FRET
• Color tuning achieved by acceptor concentration and temperature

Pulse Analysis

Persistent luminescence materials have attracted attention for their ability to emit light long after excitation, a property leveraged in anti‑counterfeiting inks, temperature sensors, and bioimaging probes. However, most organic emitters suffer severe thermal quenching, losing afterglow intensity once the device exceeds modest temperatures. Inorganic hosts such as boric acid can rigidify molecular environments and suppress vibrational losses, yet their conventional high‑temperature processing often degrades delicate organic dopants and limits color versatility. Overcoming these trade‑offs is essential for expanding luminescent technologies into harsher operational settings.

The new study circumvents the temperature barrier by embedding triphenylboronic acid (TPBA) into a boric acid matrix that crystallizes at just 120 °C. This mild thermal treatment creates a metaborate network that physically confines TPBA, extending its phosphorescence lifetime to 2.56 seconds even at 460 K. Crucially, the researchers introduced Rhodamine 6G as a FRET acceptor, harvesting the blue‑green triplet emission and re‑radiating it as red fluorescence. By varying the Rhodamine concentration or the ambient temperature, the afterglow hue can be fine‑tuned with high precision, demonstrating a scalable route to multicolor high‑temperature afterglow.

The ability to produce stable, tunable afterglow at elevated temperatures positions this organic‑inorganic hybrid as a versatile platform for next‑generation security features and smart sensors that must operate under harsh conditions. Dynamic color control enables multiplexed encoding, where different hues correspond to distinct verification levels or temperature thresholds. Moreover, the low‑temperature synthesis preserves the integrity of sensitive organic dyes, opening pathways for integrating bio‑compatible fluorophores in high‑temperature applications. As industries seek more resilient luminescent markers, this FRET‑based strategy could accelerate commercialization of advanced anti‑counterfeit tags and temperature‑responsive diagnostic tools.