College of Physics and Electronics Engineering & College of Chemistry and Materials Science, Hengyang Normal University, Hengyang, 421008, China.
Beijing Computational Science Research Center, Beijing, 100084, China.
Sci Rep. 2017 Aug 10;7(1):7843. doi: 10.1038/s41598-017-08215-3.
The suitable band structure is vital for perovskite solar cells, which greatly affect the high photoelectric conversion efficiency. Cation substitution is an effective approach to tune the electric structure, carrier concentration, and optical absorption of hybrid lead iodine perovskites. In this work, the electronic structures and optical properties of cation (Bi, Sn, and TI) doped tetragonal formamidinium lead iodine CH(NH)PbI (FAPbI) are studied by first-principles calculations. For comparison, the cation-doped tetragonal methylammonium lead iodine CHNHPbI (MAPbI) are also considered. The calculated formation energies reveal that the Sn atom is easier to dope in the tetragonal MAPbI/FAPbI structure due to the small formation energy of about 0.3 eV. Besides, the band gap of Sn-doped MAPbI/FAPbI is 1.30/1.40 eV, which is considerably smaller than the un-doped tetragonal MAPbI/FAPbI. More importantly, compare with the un-doped tetragonal MAPbI/FAPbI, the Sn-doped MAPbI and FAPbI have the larger optical absorption coefficient and theoretical maximum efficiency, especially for Sn-doped FAPbI. The lower formation energy, suitable band gap and outstanding optical absorption of the Sn-doped FAPbI make it promising candidates for high-efficient perovskite cells.
合适的能带结构对钙钛矿太阳能电池至关重要，它会极大地影响光电转换效率。阳离子取代是一种有效的方法，可以调整钙钛矿卤化物的电子结构、载流子浓度和光学吸收。在这项工作中，通过第一性原理计算研究了阳离子（Bi、Sn 和 TI）掺杂四方 formamidinium 铅碘 CH(NH)PbI（FAPbI）的电子结构和光学性质。为了进行比较，还考虑了阳离子掺杂的四方甲基碘化铵铅 CHNHPbI（MAPbI）。计算的形成能表明，由于约 0.3eV 的小形成能，Sn 原子更容易在四方 MAPbI/FAPbI 结构中掺杂。此外，Sn 掺杂的 MAPbI/FAPbI 的能带隙为 1.30/1.40eV，比未掺杂的四方 MAPbI/FAPbI 小得多。更重要的是，与未掺杂的四方 MAPbI/FAPbI 相比，Sn 掺杂的 MAPbI 和 FAPbI 具有更大的光学吸收系数和理论最大效率，尤其是 Sn 掺杂的 FAPbI。Sn 掺杂的 FAPbI 较低的形成能、合适的能带隙和出色的光学吸收使它成为高效钙钛矿电池的有前途的候选材料。
