Tuning the Band Gaps of Oxide and Halide Perovskite Compounds via Biaxial Strain in All Directions
Tuning the Band Gaps of Oxide and Halide Perovskite Compounds via Biaxial Strain in All Directions
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DOI：
10.1021/acs.jpcc.1c07169
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发表时间：
2021-11
期刊：
影响因子：
--
通讯作者：
Corey Teply;B. Tyler;R. Berger
中科院分区：
文献类型：
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作者：
Corey Teply;B. Tyler;R. Berger
氧化物和卤化物族中的过氧化物化合物分别作为光催化和光伏应用的光吸收剂引起了人们的兴趣。在这两类中，双轴应变可用于调节结构变形，从而调节带隙和太阳能转换效率。虽然应变通常是垂直于立方钙钛矿晶胞轴（即，001方向），其它晶体学方向上的应变为电子结构或甚至同一材料内的局部带隙范围的定性不同变化提供了机会。对于氧化物（钛酸钡）和卤化物（CsGeX3）钙钛矿在室温下的极性铁电畸变，目前的工作探讨了如何以及为什么应变在所有的晶体方向调谐带隙和带边轨道。它是确定的，由于可追溯到原子轨道在带边的相互作用的原因，可实现的压缩双轴应变下的氧化物和卤化物的化合物的带隙变化的十分之几个电子伏特取决于应变的方向。值得注意的是，CsGeI3中可获得的带隙范围预计将跨越太阳光谱中最强烈的区域。
Perovskite compounds in the oxide and halide families have generated interest as light absorbers for photocatalytic and photovoltaic applications, respectively. In both of these classes, biaxial strain can be used to tune structural distortions and, consequently, band gaps and solar energy conversion efficiencies. While strain has usually been explored perpendicular to the cubic perovskite unit cell axis (i.e., the 001 direction), strain in other crystallographic directions presents opportunities for qualitatively different changes to the electronic structure or even a range of local band gaps within the same material. For oxide (BaTiO3) and halide (CsGeX3) perovskites with polar ferroelectric distortions at room temperature, the present work explores how and why strain in all crystallographic directions tunes the band gap and band-edge orbitals. It is determined that, for reasons traceable to the interactions of atomic orbitals at the band edges, the band gaps of both oxide and halide compounds under achievable compressive biaxial strains vary by several tenths of an eV depending on the direction of strain. Notably, the range of band gaps accessible in CsGeI3is predicted to span the most intense regions of the solar spectrum.