Engineering of Perovskite Materials Based on Formamidinium and Cesium Hybridization for High-Efficiency Solar Cells 

Daniel Prochowicz, Rashmi Runjhun, Mohammad Mahdi Tavakoli, Pankaj Yadav, Marcin Saski, Anwar Q. Alanazi, Dominik J. Kubicki, Zbigniew Kaszkur, Shaik M. Zakeeruddin, Janusz Lewinski, and Michael Grätzel 

Chem. Mater. (2019) 31, 1620−1627


Engineering  the  chemical composition  of  inorganic-organic  hybrid  perovskite  materials  is  an  effective strategy to boost the performance and operational stability of perovskite solar cells (PSCs). Among the diverse   family   of   ABX3 perovskites,   methylammonium-free   mixed   A-site   cation CsxFA1‐xPbI3 perovskites  appear  as  attractive  light  absorber  materials  due  to  their  optimum  bandgap,  superior optoelectronic property,  and good thermal stability. Here,we develop a simple and very effective one-step  solution  method  for  the  preparation  of high-quality  (Cs)x(FA)1-xPbIperovskite  films  upon  the addition  of  excess  CsCl  to  the  FAPbI3 precursor  solution.  It  is  found  that  the  addition  of  CsCl  as  a source  of  Cs  cation  instead  of  relevant  addition  of  CsI to  the  parent  perovskite  solution increases effectively  the  grain  size  and  film quality leading  to  improved  charge  mobility,  reduced  carrier recombination  and  long  carrier  life  time.  The  resultant  mesoscopic  perovskite  devices  exhibit a maximum  efficiency  of  20.60%  with  a  stabilized  PCE  of  19.85% and lower  hysteresis compared  to  the reference  device.  This  performance  is  among  of  the  highest  reported  for  PSC  devices  incorporating mixed cation (Cs)x(FA)1-xPbIperovskites.

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This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 711859.