Abstract
We report blue, green, and red upconversion emissions with strongly angular-dependent intensities for a new type of hybrid (Y,Yb,Er)–pyrazine thin films realized using the atomic/molecular layer deposition thin-film fabrication technology. The luminescence emissions in our amorphous (Y,Yb,Er)–pyrazine thin films of a controllable nanothickness originate from three- and two-photon NIR-to-vis excitation processes. In addition to shielding the lanthanide ions from nonradiative de-excitation, the network of interconnected organic molecules serves as an excellent matrix for the Yb3+-to-Er3+ excitation energy transfer. This suggests a new approach to achieve efficient upconverting molecular materials with the potential to be used for next-generation medical diagnostics, waveguides, and surface-sensitive detectors.
Highlights
Photon upconversion is a phenomenon where lower energy photons are piled up to create higher energy photons.[1]
We demonstrate that our ALD/MLD process for the (Y,Yb,Er)−pyrazine thin films from (Y,Yb,Er)(thd)[3] and pyrazinedicarboxylic acid precursors works in the expected ideal atomic/molecular layer-by-layer deposition mode
We may conclude that our (Y,Yb,Er)(thd)3 + pyrazinedicarboxylic acid ALD/MLD process yields highquality thin films through self-limiting gas−surface reactions of the precursors with the selected ALD/MLD parameters in the deposition temperature range of 160−225 °C
Summary
Photon upconversion is a phenomenon where lower energy photons are piled up to create higher energy photons.[1]. The ALD/MLD technology has several other inherent advantages highly relevant to advanced upconversion applications in e.g. medical diagnostics, such as the possibility to use the technique for (sub)nanoscale surface functionalization of various complex surface architectures,[35,36] and low-temperature deposition of flexible hybrid coatings on sensitive or demanding substrates such as polymers, textiles,[37] or biomaterials.[38] Very recently, we reported the ALD growth of highly homogeneous upconverting inorganic (Yb,Er)2O3 thin films.[39] In the present work, we demonstrate for the first time the NIR-to-vis lanthanide upconversion emission for ALD/MLD-fabricated molecular inorganic−organic thin films. The latter observation is extremely intriguing for application in ultrasensitive fluorescence assays and surface sensors for point-of-care diagnostics.[42−46]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
