Tellurium-Based Double Perovskites A₂TeX₆ with Tunable Band Gap and Long Carrier Diffusion Length for Optoelectronic Applications

Lead-free hybrid perovskites have attracted immense interest as environmentally friendly light absorbers. Here, we report on tellurium (Te)-based double perovskites A2TeX6 (A = MA, FA, or BA; X = Br– or I–; MA = CH3NH3; FA = CH­(NH2)2; BA = benzylamine) as potentially active materials for optoelectronic devices. These perovskites exhibit a tunable band gap (1.42–2.02 eV), a low trap density (∼1010 cm–3), and a high mobility (∼65 cm2 V–1 s–1). Encouragingly, the MA2TeBr6 single crystal with a band gap of 2.00 eV possesses a long carrier lifetime of ∼6 μs and corresponding carrier diffusion lengths of ∼38 μm, which are ideal characteristics for a material for photodetectors and tandem solar cells. Moreover, A2TeX6 perovskites are relatively robust in ambient conditions, being stable for at least two months without showing any signs of phase change. Our findings bring to the forefront a family of lead-free Te-based perovskites for nontoxic perovskite optoelectronics.无铅混合钙钛矿（Lead-free hybrid perovskites）作为环保型光吸收材料受到了广泛关注。本文报道了基于碲（Te）的双钙钛矿A₂TeX₆（其中A为甲胺（MA, CH₃NH₃）、甲脒（FA, CH(NH₂)₂）或苄胺（BA）；X为溴离子（Br⁻）或碘离子（I⁻）），将其作为光电子器件的潜在活性材料。该类钙钛矿展现出可调谐带隙（1.42~2.02 eV）、低陷阱密度（~10¹⁰ cm⁻³）以及高迁移率（~65 cm²·V⁻¹·s⁻¹）。令人鼓舞的是，带隙为2.00 eV的MA₂TeBr₆单晶具有约6 μs的长载流子寿命，以及约38 μm的载流子扩散长度，这些特性使其成为光电探测器和叠层太阳能电池的理想材料。此外，A₂TeX₆钙钛矿在大气环境中表现出较好的稳定性，可稳定保存至少两个月且未出现任何相变迹象。本研究将一类无铅碲基钙钛矿推至非毒性钙钛矿光电子学研究的前沿。