Full-featured spectral converter enabled by coupling quench-resistant organic luminophore with lanthanide nanocrystals

Spectral converters with satisfactory absorption cross-section, luminescence efficiency, and photostability are of great significance for improving photoelectric conversion performances in optoelectronics, but the integration of these features remains an open challenge. Here we fabricate a full-featured spectral converter by integrating benzothiadiazole derivatives (BDB) and Nd³⁺/Yb³⁺ ions co-doped nanocrystals (Nd/Yb NCs). BDB molecules are selected due to their excellent anti-quenching properties in the solid state. The coupling of BDB molecules to Nd/Yb NCs (BDB@Nd/Yb NCs), on the one hand, diminishes the negative molecular reabsorption through red-shifting the emission spectrum. On the other hand, Nd³⁺/Yb³⁺ couples showing downshifting effect provide an additional radiative channel for stimulated BDB molecules. As a result, Hybridized BDB@Nd/Yb NCs, encapsulated in a transparent polymer film, are endowed with near-unity spectral conversion efficiency, ultra-wide absorption window from 300 to 550 nm and photostability over 90 days under ambient conditions. With the help of BDB@Nd/Yb films, the photovoltaic conversion efficiency of silicon solar cells has been absolutely increased by 2.80 %, highlighting their promising future in photovoltaic devices. This work paves a new direction for fabricating the next generation of spectral converters.