Perovskite solar cells (PSCs), have made tremendous progress but are still far away from theoretically estimated power conversion efficiencies (PCEs) and commercialization. Defects present in the perovskite materials and at various interfaces (between ETL/HTL and perovskite) in devices are inhibiting the performance to get closer to the theoretical limits, whereas the controlled atmosphere fabrication is creating a bottleneck in large scale production. Therefore, meticulous attention is required to overcome these problems. In this work, we report a very simple, facile and efficient post-synthesis surface treatment with methyl ammonium iodide (MAI) for surface and grain boundary defect passivation in the PSCs processed in fully ambient atmosphere. Ambient atmosphere, MAI surface treatment showed synergetic improvement, firstly it healed the defects (iodine trap states) existing on the surface/interface and grain boundaries and secondly increased the grain size, thereby reducing the defect sites. The improved crystallinity, morphology and decreased defects, reduced the trap density and non-radiative recombination losses leading to fast charge extraction. As a result, planar (n-i-p) PSCs, passivated with optimum MAI concentration, showed significantly higher boost (14%) in the power conversion efficiency (PCE) compared to previous MAI surface treatments, where no morphological changes were observed.
Bibliographical noteFunding Information:
This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, South Korea (NRF-2019R1A6A1A11055660).
© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films