Related Experiment Video
Updated: Feb 25, 2026
Influence of Hybrid Perovskite Fabrication Methods on Film Formation, Electronic Structure, and Solar Cell Performance
Published on: February 27, 2017
Interfacial Modification of Perovskite Solar Cells Using an Ultrathin MAI Layer Leads to Enhanced Energy Level
Zafer Hawash1, Sonia R Raga1, Dae-Yong Son2
1Energy Materials and Surface Sciences Unit (EMSS), Okinawa Institute of Science and Technology Graduate University (OIST) , 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan.
Abstract:
For the first time, we intentionally deposit an ultrathin layer of excess methylammonium iodide (MAI) on top of a methylammonium lead iodide (MAPI) perovskite film. Using photoelectron spectroscopy, we investigate the role of excess MAI at the interface between perovskite and spiro-MeOTAD hole-transport layer in standard structure perovskite solar cells (PSCs). We found that interfacial, favorable, energy-level tuning of the MAPI film can be achieved by controlling the amount of excess MAI on top of the MAPI film. Our XPS results reveal that MAI dissociates at low thicknesses (<16 nm) when deposited on MAPbI3. It is not the MAI layer but the dissociated species that leads to the interfacial energy-level tuning. Optimized interface energetics were verified by solar cell device testing, leading to both an increase of 19% in average steady-state power conversion efficiency (PCE) and significantly improved reproducibility, which is represented by a much lower PCE standard deviation (from 15 ± 2% to 17.2 ± 0.4%).
