Green, red and near-infrared photon up-conversion in Ga–Ge–Sb–S:Er3+ amorphous chalcogenides

We report on compositional tuning in Er3+ ions doped Ga–Ge–Sb–S glassy system allowing for effective 2H11/2→4I15/2 (530 nm), 4S3/2→4I15/2 (550 nm), 4F9/2→4I15/2 (660 nm), 4I9/2→4I15/2 (810 nm), 4I11/2→4I15/2 (990 nm) intra-4f electronic transition emissions of Er3+ ions under 808 nm, 980 nm or 1550 nm laser pumping. We changed the composition of well-known Ge20Ga5Sb10S65 glass to Ge25Ga10−xSbxS65, where x=0.5 at%, 2.5 at% or 5.0 at% and doped it with 0.5 at% of Er3+ ions. The short-wavelength absorption edge of the studied glassy hosts is blue-shifted by substitution of Sb with Ga to ∼500 nm making the green emission at 530 nm and 550 nm and even 495 nm (4F7/2→4I15/2) observable, while the glass stability was kept high characterized with the difference of Tc−Tg>100 K and mean coordination numbers 2.67–2.71. Up-conversion emission decay times of all anti-Stokes emissions were in the range of 0.2–2.1 ms. The influence of Ga substitution with Sb on the structure and the optical properties was investigated. The spectroscopic parameters for Er3+ ions with local environment change were analyzed based on Judd–Ofelt theory. -- Highlights: • Compositional tuning of Ga–Ge–Sb–S:Er3+ phosphor leads to efficient photon up-conversion under 808 nm, 980 nm and 1550 nm laser pumping. • The 530 nm, 550 nm, 660 nm, 810 nm and 990 nm up-conversion emission bands were detected and their lifetimes determined. • Judd–Ofelt theory was used to study the Er3+ local environment in Ga–Ge–Sb–S glassy host matrix. • Thermally stable chalcogenide Ga–Ge–Sb–S:Er3+ phosphors are proposed as candidates for up-converting layers enhancing the silicon solar cell efficiency