Strong Near-Infrared Luminescence in BaSnO₃

Abstract

Powdered samples of the perovskite BaSnO(3) exhibit strong near-infrared (NIR) luminescence at room temperature, following band-gap excitation at 380 nm (3.26 eV). The emission spectrum is characterized by a broad band centered at 905 nm (1.4 eV), tailing on the high-energy side to approximately 760 nm. The Stokes shift is 1.9 eV, and measured lifetimes in the range 7-18 ms depend on preparative conditions. These extraordinary long values indicate that the luminescence involves a defect state(s). At low temperatures, both a sharp peak and a broad band appear in the visible portion of the luminescence spectrum at approximately 595 nm. Upon cooling, the intensity of the NIR emission decreases, while the integrated intensities of the visible emission features increase to approximately 40% of the NIR intensity at 77 K. Room-temperature photoluminescence (PL) is observed across the Ba(1-x)Sr(x)SnO(3) series. As the strontium content increases, the excitation maximum and band gap shift further into the UV, while the intensity of the NIR emission peak decreases and shifts further into the infrared. This combination leads to an unexpectedly large increase in the Stokes shift. The unusual NIR PL in BaSnO(3) may originate from recombination of a photogenerated valence-band hole and an occupied donor level, probably associated with a Sn(2+) ion situated roughly 1.4 eV above the valence-band edge.

Theoretical band energetics of Ba(M0.5Sn0.5)O3 for solar photoactive applications

“…8,25 In spite of such underestimation of the calculated band gap, we believe that present type of qualitative study can be worthwhile on relative scale specially for photocatalytic applications. The correctness of the present computational and empirical approach is tested and is evidenced by the case study of TiO 2 , a well known photocatalyst.…”

“…The BaSnO 3 , a cubic perovskite structure ͑space group Pm3m͒ and a unique n-type semiconducting metal oxide with a band gap of 3.4 eV, 6,7 has been reported for its potential in optical, 8 dielectric, 9,10 and gas sensor applications. It has been sought recently to be an effective matrix for doping to achieve improved electrical properties.…”

Synthesis, Characterization, Optical and Transport Properties of BaSnO<SUB>3</SUB> Synthesized by Wet Chemical Route

“…Materials Sciences and Applications ing the general chemical formula MSnO 3 (M = Ca, Ba, Sr) and has been studied widely due to their potential applications in the field of thermally stable capacitors, photo catalyst, chemiresistive sensor materials for toxic and noxious gases [1]- [6]. It stabilizes in cubic perovskite structure at room temperature (space group Pm-3 m) with lattice parameter slightly varying from 0.4117 -0.4119 nm depending upon the method of synthesis used [7] [8] [9] [10], and behaves like n-type semiconductor with an optical band gap reported from 3.1 -3.4 eV [11] [12] [13] [14]. BaSnO 3 (BSO)compositions have been widely investigated with a view to improving the sensor response for a number of target gases including NH 3 , Co, H 2 , Cl 2 , LPG, ethanol, NO x , humidity, O 2 , etc.…”

Band gap tuning of lead-substituted BaSnO3 for visible light photocatalysis

“…The computed BG for BaSnO 3 ͑around 0.9 eV͒ is much less than the experimental BG of 3.4 eV, 9 yet the theoretical result is in good agreement with the earlier reports. 10 Though the underestimation of BG energy is a well known shortcoming of the single particle Kohn-Sham approach, 9 the predicted trends in the band gap and the qualitative features of band states can be used to interpret the physicochemical behavior of a system. As shown in Fig.…”