Boosting the Er3+ 1.5 mu m Luminescence in CsPbCl3 Perovskite Nanocrystals for Photonic Devices Operating at Telecommunication Wavelengths

CsPb(Cl1-xBrx)(3) perovskite nanocrystals (NCs) doped with Yb3+ ions have recently attracted large attention for their applications in photovoltaics in view of the high quantum yield, exceeding 100% of Yb3+ emission at similar to 1 mu m. In contrast, the particularly relevant Er3+ emission at 1.5 mu m in the third telecommunication window, of high interest in silicon integrated photonics, has been so far largely neglected in view of the weak emission performance displayed by Er3+-doped NCs. Comprehensive steady-state and time-resolved spectroscopic measurements provide insights into the underlying mechanisms of Yb3+ and Er3+ sensitization to rationalize the anomalous different behavior of these two emitters in singly doped NCs. We propose that single-photon excitation of two Yb3+ ions possibly occurs through a transient internal redox mechanism in the perovskite host, while this pathway is unviable for Er3+. In turn, Yb3+-bridged Er3+ sensitization, boosts the Er3+ luminescence at similar to 1.5 mu m by 10(4)-fold compared to Er(3+ )singly doped NCs, and a relative high quantum yield of similar to 6% and extremely long lifetime (similar to 3 ms) are obtained. The resulting high Er3+ excited state densities, combined with the large absorption cross-sections of the semiconducting CsPbCl3 matrix make Er3+-doped perovskite promising innovative materials to realize photonic devices operating at telecommunication wavelengths.