Cesium compounds as interface modifiers for stable and efficient perovskite solar cells

Research paper by Md Arafat Mahmud, Naveen Kumar Elumalai; Mushfika Baishakhi Upama; Dian Wang; Vinicius R. Gonçales; Matthew Wright; John Justin Gooding; Faiazul Haque; Cheng Xu; Ashraf Uddin

Indexed on: 14 Dec '17Published on: 12 Dec '17Published in: Annales d'oto-laryngologie et de chirurgie cervico faciale : bulletin de la Societe d'oto-laryngologie des hopitaux de Paris


Publication date: January 2018 Source:Solar Energy Materials and Solar Cells, Volume 174 Author(s): Md Arafat Mahmud, Naveen Kumar Elumalai, Mushfika Baishakhi Upama, Dian Wang, Vinicius R. Gonçales, Matthew Wright, John Justin Gooding, Faiazul Haque, Cheng Xu, Ashraf Uddin The presented work demonstrates the development of highly stable low temperature processed Cesium compound incorporated ZnO electron transport layer (ETL) for perovskite solar cells (PSCs). Cesium compounds such as CA (cesium acetate) and CC (cesium carbonate) modified ETLs are employed for fabricating highly efficient (PCE: ~ 16.5%) mixed organic cation based MA0.6FA0.4PbI3 PSCs via restricted volume solvent annealing (RVSA) method. Here, CA ETL demonstrates a 50meV upshift in Fermi level position with respect to CC ETL, contributing to higher n-type conductivity and lower electron injection barrier at the interface. Furthermore, CA ETL also exhibits profound influence on the perovskite microstructure leading to larger grain size and uniform distribution. Cesium acetate incorporated devices exhibit about 82% higher PCE compared to conventional CC devices. In addition to higher photovoltaic performance, CA devices exhibit mitigated photo-current hysteresis phenomena compared to CC devices, owing to suppressed electrode polarization phenomena. Besides, the stability of the CA devices are 400% higher than the conventional CC devices, retaining almost 90% of its initial PCE even after a month-long (30 days) systematic degradation study. The mechanism behind superior performance and stability is investigated and discussed comprehensively.