Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (6): 1439-1445.doi: 10.3866/PKU.WHXB201603154

• ARTICLE • Previous Articles     Next Articles

First-Principles Investigation of the Structural and Photoelectronic Properties of CH3NH3PbxSn1-xI3 Mixed Perovskites

Xiao-Qing LU*(),Zi-Gang ZHAO,Ke LI,Shu-Xian WEI,Yuan-Yuan QU,Yong-Qiang NIU,Xue-Feng LIU*()   

  • Received:2016-01-06 Published:2016-06-03
  • Contact: Xiao-Qing LU,Xue-Feng LIU E-mail:luxq@upc.edu.cn;liuxf@upc.edu.cn
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(21303266);Fundamental Research Funds for the Central Universities, China(15CX05050A, 14CX02214A)

Abstract:

Organic/inorganic perovskites have exhibited great potential as photoelectronic materials, achieving remarkable photoelectric conversion efficiency, currently over 20%. The structural, electronic, and optical properties of organic/inorganic hybrid CH3NH3PbxSn1-xI3 perovskites (x = 0-1) have been investigated by the first-principles theory. Our results indicate that the van der Waals (VDW) interaction plays a crucial role in the structure optimization. Accounting for VDW force correction, both the Pb/Sn―I bond lengths and volumes are decreased. By analyzing the density of states and the Bader charge of CH3NH3+ cations, we find that cations contribute only slightly to the band edge, but play the role of charge donors. There exists a combined covalent and ionic interaction between Pb/Sn and I ions. The valence band maximum (VBM) is mainly contributed by the I 5p orbitals with the overlapping of Pb 6s (Sn 5s) orbitals, while the conduction band minimum (CBM) is dominated by Pb 6p (Sn 5p) orbitals. In the visible light region, with increasing wavelength, the absorption intensity demonstrates a decreasing trend; as the Sn/Pb ratio increases, the absorption intensity shows an increasing trend. CH3NH3SnI3 perovskites demonstrate great potential to absorb light in the visible region.

Key words: Perovskite, Photoelectric property, Band structure, Density of states, Dielectric function, First-principles theory

MSC2000: 

  • O641