Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States.
Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, 110 8th Street, Troy, New York 12180, United States.
ACS Appl Mater Interfaces. 2023 Apr 19;15(15):18962-18972. doi: 10.1021/acsami.3c00618. Epub 2023 Apr 4.
The non-toxic and stable chalcogenide perovskite BaZrS fulfills many key optoelectronic properties for a high-efficiency photovoltaic material. It has been shown to possess a direct band gap with a large absorption coefficient and good carrier mobility values. With a reported band gap of 1.7-1.8 eV, BaZrS is a good candidate for tandem solar cell materials; however, its band gap is significantly larger than the optimal value for a high-efficiency single-junction solar cell (∼1.3 eV, Shockley-Queisser limit)─thus doping is required to lower the band gap. By combining first-principles calculations and machine learning algorithms, we are able to identify and predict the best dopants for the BaZrS perovskites for potential future photovoltaic devices with a band gap within the Shockley-Queisser limit. It is found that the Ca dopant at the Ba site or Ti dopant at the Zr site is the best candidate dopant. Based on this information, we report for the first time partial doping at the Ba site in BaZrS with Ca (i.e., BaCaZrS) and compare its photoluminescence with Ti-doped perovskites [i.e., Ba(ZrTi)S]. Synthesized (Ba,Ca)ZrS perovskites show a reduction in the band gap from ∼1.75 to ∼1.26 eV with <2 atom % Ca doping. Our results indicate that for the purpose of band gap tuning for photovoltaic applications, Ca-doping at the Ba-site is superior to Ti-doping at the Zr-site reported previously.
无毒且稳定的硫属卤化物钙钛矿 BaZrS 满足高效光伏材料的许多关键光电性能。研究表明，它具有直接带隙、大吸收系数和良好的载流子迁移率值。报道的带隙为 1.7-1.8 eV，BaZrS 是串联太阳能电池材料的良好候选材料；然而，其带隙明显大于高效单结太阳能电池（1.3 eV，肖克利-奎塞尔限制）的最佳值，因此需要掺杂来降低带隙。通过结合第一性原理计算和机器学习算法，我们能够识别和预测 BaZrS 钙钛矿的最佳掺杂剂，以用于未来具有肖克利-奎塞尔限制内带隙的光伏器件。研究发现，Ba 位的 Ca 掺杂或 Zr 位的 Ti 掺杂是最佳候选掺杂剂。基于此信息，我们首次报道了 BaZrS 中 Ba 位的部分掺杂（即 BaCaZrS），并将其与 Ti 掺杂的钙钛矿（即 Ba(ZrTi)S）的光致发光进行了比较。合成的（Ba，Ca）ZrS 钙钛矿的带隙从1.75 降至~1.26 eV，掺杂量小于 2 原子%。我们的结果表明，对于光伏应用的带隙调谐目的，Ba 位的 Ca 掺杂优于先前报道的 Zr 位的 Ti 掺杂。
