Erbium (Er) complexes are used as optical gain materials for signal generation in the telecom C-band at 1540 nm, but they need a sensitizer to enhance absorption. Na⁺ substitution for Ag⁺ and Bi³⁺ doping at the In³⁺ site is a possible strategy to enhance the broadband emission of Cs₂AgInCl₆, which could be used as a sensitizer for energy transfer to rare-earth elements. Herein, self-trapped exciton (STE) energy transfer to Er³⁺ at 1540 nm in double perovskite is reported. An acid precipitation method was used to synthesize Cs₂AgInCl₆ and its derivatives with Er³⁺, Bi³⁺, and Na⁺. Bare Cs₂AgInCl₆:Er emission signals were found to be weak at 1540 nm, but Bi³⁺ doping increased them by 12 times, and Bi³⁺ and Na⁺ doping increased signal intensity by up to 25 times. Electron paramagnetic resonance spectroscopy characterized a decrease in axial symmetry over the Er³⁺ ions after the substitutions of Na⁺ and Bi³⁺ in Cs₂AgInCl₆ at low temperatures (<7 K) for the first time. Moreover, an increase in pressure compressed the structure, which tuned the STE transition for free exciton emission, and a further increase in pressure distorted the cubic phase above 70 kbar.

中文翻译：

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Bi3+/Er3+ 共掺杂 Cs2Ag0.4Na0.6InCl6 双钙钛矿中自陷激子和近红外发射的增强

铒 (Er) 络合物用作光学增益材料，用于在 1540 nm 的电信 C 波段中生成信号，但它们需要敏化剂来增强吸收。在 In ³⁺位置用Na ⁺取代 Ag ⁺和 Bi ^{3+掺杂是增强 Cs} ₂ AgInCl ₆宽带发射的可能策略，它可以用作能量转移到稀土元素的敏化剂。在此，报道了在双钙钛矿中自陷激子 (STE) 能量转移到 1540 nm 处的 Er ^{3+ 。}采用酸沉淀法合成Cs ₂ AgInCl ₆及其与Er ³⁺、Bi³⁺和 Na ⁺。发现裸 Cs ₂ AgInCl ₆ :Er 发射信号在 1540 nm 处较弱，但 Bi ³⁺掺杂使它们增加了 12 倍，而 Bi ³⁺和 Na ⁺掺杂使信号强度增加了高达 25 倍。电子顺磁共振波谱表征在 Cs ₂ AgInCl ₆中取代 Na ⁺和 Bi ^{3+后 Er 3+}离子的轴对称性降低首次在低温（<7 K）下。此外，压力的增加压缩了结构，从而调整了自由激子发射的 STE 跃迁，并且压力的进一步增加使立方相在 70 kbar 以上扭曲。