近十年來，ns2陽離子（如Pb2+和Sn2+）基鹵化物（如混合鈣鈦礦太陽能吸收劑等）已成為最令人興奮的光電子材料新類別之一。這些材料不僅在某些情況下表現出前所未見的性能，且可能以其優異的性能（如對缺陷的極端耐受性）打開一片新天地。然而，此類材料才剛出現不久，其很多化合物尚未得到充分的探索。來自吉林大學、密蘇里大學和阿肯色州立大學的科研人員，采用連貫第一性原理法研究了一系列鉍/銻鹵氧化物和硫鹵化物的性質及其規律。他們驚奇地發現，一些鉍基硫鹵化物（帶隙范圍為1.5~2eV）有望用于太陽能電池和室溫輻射探測器；而它們的鹵氧化物（帶隙高于3 eV），則由空穴傳導，若被摻雜，可用作透明導電材料。在此基礎上，合作者們進而探討了這些化合物的電子結構及其與晶體幾何結構的關系，以及對帶邊擴散和載流子有效質量的影響。作者們據此認為，有必要對該類潛在的光電子應用材料作進一步實驗研究，為其在太陽能電池等方面的應用奠定基礎。該文近期發表于npj Computational Materials 4:14(2018); doi:10.1038/s41524-018-0071-1。

Bismuth and antimony-based oxyhalides and chalcohalides as potential optoelectronic materials

Zhao Ran,Xinjiang Wang,Yuwei Li,Dongwen Yang,Xin-Gang Zhao,Koushik Biswas,David J. Singh&Lijun Zhang

In the last decade thens2cations (e.g., Pb2+andSn2+)-based halides have emerged as one of the most exciting new classes of optoelectronic materials, as exemplified by for instance hybrid perovskite solar absorbers. These materials not only exhibit unprecedented performance in some cases, but they also appear to break new ground with their unexpected properties, such as extreme tolerance to defects. However, because of the relatively recent emergence of this class of materials, there remain many yet to be fully explored compounds. Here, we assess a series of bismuth / antimony oxyhalides and chalcohalides using consistent first principles methods to ascertain their properties and obtain trends. Based on these calculations, we identify a subset consisting of three types of compounds that may be promising as solar absorbers, transparent conductors, and radiation detectors. Their electronic structure, connection to the crystal geometry, and impact on band-edge dispersion and carrier effective mass are discussed.