Reduction in the Interfacial Trap Density of Perovskites

ACS Appl. Mater. Interfaces, 2017, 34, 28418–28425.

 

Reduction in the Interfacial Trap Density of Mechanochemically Synthesized MAPbI3


Daniel Prochowicz,a,b Pankaj Yadav,a Michael Saliba,a Marcin Saskib Shaik M. Zakeeruddin,a Janusz Lewinski,b,c Michael Grätzel,a

a Laboratory of Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
b Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland
c Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland

DOI: 10.1021/acsami.7b06788
First published online: 9 August 2017
Paper at Publisher’s website

Organo-lead halide perovskites have emerged as a promising light harvesting materials for solar cells. The ability to prepare high quality films with a low concentration of defects is essential for obtaining high device performance. Here, we advance the procedure for the fabrication of efficient perovskite solar cells (PSCs) based on mechanochemically synthesized MAPbI3. The use of mechano-perovskite for the thin film formation provides a high degree of control of the stoichiometry and allows for the growth of relatively large crystalline grains. The best device achieved a maximum PCE of 17.5% from a current-voltage scan (J-V), which stabilized at 16.8% after 60 sec of maximum power point tracking. Strikingly, PSCs based on MAPbI3 mechanoperovskite exhibit lower “hysteretic” behaviour in comparison to that comprising MAPbI3 obtained from the conventional solvothermal reaction between PbI2 and MAI. To gain a better understanding of the difference in J–V hysteresis we analyze the charge/ion accumulation mechanism and identify the defect energy distribution in the resulting MAPbI3 based devices. These results indicate that the use of mechanochemically synthesized perovskites provides a promising strategy for the formation of crystalline film demonstrating slow charge recombination and low trap density.