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

All-inorganic perovskite(CsPbX3)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(CsPbCl3 NCs)to ytterbium ions(Yb3+)as an NIR emitter doped in perovskite NCs.The optimized CsPbCl3 NC with 15 mol%Yb3+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/CsPbCl3:15 mol%Yb3+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?.The introduction of Yb3+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.

Sn content gradient GeSn with strain controlled for high performance GeSn mid-infrared photodetectors

GeSn detectors have attracted a lot of attention for mid-infrared Si photonics,due to their compatibility with Si complementary metal oxide semiconductor technology.The GeSn bandgap can be affected by Sn composition and strain,which determines the working wavelength range of detectors.Applying the Sn content gradient GeSn layer structure,the strain of GeSn can be controlled from fully strained to completely relaxed.In this work,the strain evolution of GeSn alloys was investigated,and the effectiveness of gradually increasing Sn composition for the growth of high-Sn-content GeSn alloys was revealed.Relaxed GeSn thick films with Sn composition up to 16.3%were grown,and GeSn photodetectors were fabricated.At 77 K,the photodetectors showed a cutoff wavelength up to 4.2μm and a peak responsivity of 0.35 A/W under 1 V at 2.53μm.These results indicate that GeSn alloys grown on a Sn content gradient GeSn structure have promising application in mid-infrared detection.