980 nm Near-Infrared Light-Emitting Diode Using All-Inorganic Perovskite Nanocrystals Doped with Ytterbium Ions

All-inorganic perovskite (CsPbX ${}_{\mathrm{3}}$) nanocrystals (NCs) have recently been widely investigated as versatile solution-processable light-emitting materials. Due to its wide-bandgap nature, the all-inorganic perovskite NC Light-Emitting Diode (LED) is limited to the visible region (400–700 nm). A particularly difficult challenge lies in the practical application of perovskite NCs in the infrared-spectrum region. In this work, a 980 nm NIR all-inorganic perovskite NC LED is demonstrated, which is based on an efficient energy transfer from wide-bandgap materials (CsPbCl ${}_{\mathrm{3}}$ NCs) to ytterbium ions (Yb ${}^{\mathrm{3}\mathrm{+}}$) as an NIR emitter doped in perovskite NCs. The optimized CsPbCl ${}_{\mathrm{3}}$ NC with 15 mol%Yb ${}^{\mathrm{3}\mathrm{+}}$ doping concentration has the strongest 980 nm photoluminescence (PL) peak, with a PL quantum yield of 63%. An inverted perovskite NC LED is fabricated with the structure of ITO/PEDOT: PSS/poly-TPD/CsPbCl ${}_{\mathrm{3}}$:15 mol%Yb ${}^{\mathrm{3}\mathrm{+}}$ NCs/TPBi/LiF/Al. The LED has an External Quantum Efficiency (EQE) of 0.2%, a Full Width at Half Maximum (FWHM) of 47 nm, and a maximum luminescence of 182 cd/m ${}^{\mathrm{2}}$. The introduction of Yb ${}^{\mathrm{3}\mathrm{+}}$ doping in perovskite NCs makes it possible to expand its working wavelength to near-infrared band for next-generation light sources and shows potential applications for optoelectronic integration.