Savory Christopher N, Walsh Aron, Scanlon David O
Kathleen Lonsdale Materials Chemistry, Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, United Kingdom.
Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom; Global E3 Institute and Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, South Korea.
ACS Energy Lett. 2016 Nov 11;1(5):949-955. doi: 10.1021/acsenergylett.6b00471. Epub 2016 Oct 12.
The methylammonium lead halides have become champion photoactive semiconductors for solar cell applications; however, issues still remain with respect to chemical instability and potential toxicity. Recently, the CsAgBiX (X = Cl, Br) double perovskite family has been synthesized and investigated as stable nontoxic replacements. We probe the chemical bonding, physical properties, and cation anti-site disorder of CsAgBiX and related compounds from first-principles. We demonstrate that the combination of Ag(I) and Bi(III) leads to the wide indirect band gaps with large carrier effective masses owing to a mismatch in angular momentum of the frontier atomic orbitals. The spectroscopically limited photovoltaic conversion efficiency is less than 10% for X = Cl or Br. This limitation can be overcome by replacing Ag with In or Tl; however, the resulting compounds are predicted to be unstable thermodynamically. The search for nontoxic bismuth perovskites must expand beyond the CsAgBiX motif.
甲基卤化铅已成为太阳能电池应用中备受瞩目的光活性半导体；然而，在化学稳定性和潜在毒性方面仍存在问题。最近，CsAgBiX（X = Cl、Br）双钙钛矿家族已被合成并作为稳定的无毒替代品进行研究。我们从第一性原理出发，探究CsAgBiX及相关化合物的化学键、物理性质和阳离子反位无序。我们证明，由于前沿原子轨道角动量不匹配，Ag（I）和Bi（III）的组合导致了具有大载流子有效质量的宽间接带隙。对于X = Cl或Br，光谱限制的光伏转换效率小于10%。通过用In或Tl取代Ag可以克服这一限制；然而，预测所得化合物在热力学上不稳定。寻找无毒铋基钙钛矿必须超越CsAgBiX结构。
