NIR photon downshifting via host sensitization in Yb3+-doped La2Ti2O7 and BaTi(PO4)2

UV to NIR Down-Shifting in Yb3+-Doped Phosphate Glass via Divalent Tin Centers

“…The near-infrared (NIR) emission from Yb 3+ ions has been considered valuable for optical applications such as lasing and for spectral converters aiming to boost the efficiency of silicon-based solar cells . The latter application has gained increasing attention − given the growing energy demand and climate change concerns linked to the burning of fossil fuels . Nevertheless, a challenge is presented in that Yb 3+ ions have a simple energy level structure and cannot absorb visible or ultraviolet (UV) light directly.…”

“…Nevertheless, a challenge is presented in that Yb 3+ ions have a simple energy level structure and cannot absorb visible or ultraviolet (UV) light directly. Hence, various alternatives have been explored as UV/vis sensitizers for converting high-energy photons to the NIR (950–1100 nm) in different Yb 3+ -containing hosts: rare-earth ions such as Ce 3+ , ,,, Tb 3+ , , Pr 3+ , and Eu 3+ ; other metal cations such as Bi 3+ , , Cr 3+ , and Te 4+ ; silver in the form of aggregates; and host-induced sensitization . Typical mechanisms claimed to be involved in the sensitization of Yb 3+ NIR emission are a cooperative energy transfer − or an energy transfer proceeding via charge transfer states. , The latter mechanism is specifically supported when an energy donor with a tendency to become oxidized (e.g., Tb 3+ , Ce 3+ , , ) is coupled with an acceptor susceptible for reduction (e.g., Eu 3+ , Yb 3+ ). , The search for suitable sensitizers for Yb 3+ operating via different mechanisms thus continues to be an active area of research largely stimulated by global demands for clean energy …”

“…Hence, various alternatives have been explored as UV/vis sensitizers for converting high-energy photons to the NIR (950−1100 nm) in different Yb 3+ containing hosts: rare-earth ions such as Ce 3+ , 2,4,5,10 Tb 3+ , 3,6 Pr 3+ , 7 and Eu 3+ ; 8 other metal cations such as Bi 3+ , 2,8 Cr 3+ , 8 and Te 4+ ; 9 silver in the form of aggregates; 11 and host-induced sensitization. 13 Typical mechanisms claimed to be involved in the sensitization of Yb 3+ NIR emission are a cooperative energy transfer 6−9 or an energy transfer proceeding via charge transfer states. 4,10 The latter mechanism is specifically supported when an energy donor with a tendency to become oxidized (e.g., Tb 3+ , 3 Ce 3+ , 4,5 ) is coupled with an acceptor susceptible for reduction (e.g., Eu 3+ , 3 Yb 3+ ).…”