Proceedings of Perovskite Thin Film Photovoltaics (ABXPV17)
Publication date: 18th December 2016
The impressively fast technological progress of highly efficient perovskite solar cells based on organic-anorganic lead halides such as CH3NH3PbI3 (MAPI) has made a huge impact on the photovoltaic research community. There are two main concerns linked to this technology: The device stability and the involvement of the heavy metal Pb. In consequence, major research efforts are put into the development of new material solutions and enhanced device architectures. One promising class of candidates are double perovskites, where two Pb ions (group IV) are replaced by one group III ion and one group V ion. In our contribution, we report on the successful synthesis of Cs2AgBiBr6 single crystals and their fundamental opto-electronic characterization. This lead-free double perovskite has an indirect band gap of 1.95 eV and is reported to have better stability than MAPI. Here, we report on our structural characterization by X-ray diffraction and a detailed study of the vibrational modes investigated by multi-wavelength Raman spectroscopy. In addition, we present an effective methodology to detect secondary phases in this material. We find the single crystals to be stable at ambient air conditions up to a temperature of approximately 200ºC. Finally, the potential of this material for photovoltaic applications will be discussed.