In situ boost and reversible modulation of dual-mode photoluminescence under an electric field in a tape-casting-based Er-doped K_0.5Na_0.5NbO₃ laminar ceramic

Abstract

Er-doping in KNN brings local inhomogenous chemical bonding environment and in situ electric field-induced reversible modulations of dual-mode PL.

Defect Management and Multi‐Mode Optoelectronic Manipulations via Photo‐Thermochromism in Smart Windows

“…To optimize the thermodynamic driving force and find the favorable doping positions for alkaline earth metals in the KNN crystal lattice, the 4×4×3 orthorhombic KNN supercell by including the special quasi‐random structure (SQS) approach was introduced for all the calculations. [ 17,19 ] According to the calculated formation energy with different alkaline earth metal substitutions (Figure S1, Supporting Information), the Ca/Sr/Ba dopant can replace both K and Na on the A‐site, from the thermodynamic point of view, similar to our previous work that Er dopant could mainly replace both K and Na at the A‐site. [ 19 ] And the replacements of Na are slightly easier than those of K. However, all the values are positive values, suggesting that the Mg substitution is not energetically favorable in KNN, which explains why Mg substitution is rarely achieved in KNN system.…”

“…[ 17,19 ] According to the calculated formation energy with different alkaline earth metal substitutions (Figure S1, Supporting Information), the Ca/Sr/Ba dopant can replace both K and Na on the A‐site, from the thermodynamic point of view, similar to our previous work that Er dopant could mainly replace both K and Na at the A‐site. [ 19 ] And the replacements of Na are slightly easier than those of K. However, all the values are positive values, suggesting that the Mg substitution is not energetically favorable in KNN, which explains why Mg substitution is rarely achieved in KNN system. Herein, the and values are slightly more negative than , indicating higher potential doping concentration possibility for both Sr and Ba.…”

“…The shGGA‐1/2 bandgap of perfect KNN is calculated to be 2.85 eV, which agrees well with our previous result. [ 19 ] Interestingly, the shGGA‐1/2 bandgap is apparently larger than the standard DFT results and perfectly overcomes the bandgap problem for KNN. It is worth noting that all the doping ions chosen in this work can slightly enhance the bandgap of KNN.…”

Significantly Photo‐Thermochromic KNN‐Based “Smart Window” for Sustainable Optical Data Storage and Anti‐Counterfeiting

“…Under 980 nm excitation, all the ceramics present relatively weak green emission and intense red emission, thus exhibit a clear visible high‐purity red‐emitting which has been rarely reported in KNN‐based materials. [ 18–30 ] The green emission band ranging from 515 to 565 nm was attributed to 2 H 11/2 / 4 S 3/2 → 4 I 15/2 characteristic 4 f‐ 4 f electronic transitions of Er 3+ , while the red emission band in the region from 635 to 690 nm can be assigned to 4 F 9/2 → 4 I 15/2 transition. Due to the large energy gaps of 4 S 3/2 and 4 F 9/2 , the 4 I 11/2 and 4 I 13/2 levels were relatively unfavorable for the electron population of 4 F 9/2 level.…”

Designing Photochromic Materials with Large Luminescence Modulation and Strong Photochromic Efficiency for Dual‐Mode Rewritable Optical Storage

“…[ 11–15 ] In contrast, inorganic materials exhibit superior thermal stability, excellent fatigue resistance, and facile preparation, showing great potential in optical memory applications. Different inorganic materials, such as transition metal oxides (WO 3 and TiO 2 ), [ 16–23 ] ferroelectric ceramics ((K 0.5 Na 0.5 )NbO 3 , Na 0.5 Bi 2.5 Nb 2 O 9 ) [ 23–31 ] and robust oxides (BaMgSiO 4 , Sr 2 SnO 4 ) [ 32–44 ] have been developed for photochromic applications together with the investigation of their luminescence modulation behavior. Despite the achievement of reversible luminescence modulation based on photochromic behavior, simultaneously achieving a large luminescence modulation and a strong photochromic efficiency in inorganic materials is still challenging.…”