Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells
Ratnasingham, Sinclair R.
McLachlan, Martyn A.
Kim, Ji Seon
KAUST DepartmentPhysical Science and Engineering (PSE) Division
Online Publication Date2021-10-21
Print Publication Date2021-11-12
Embargo End Date2022-10-21
Permanent link to this recordhttp://hdl.handle.net/10754/672936
MetadataShow full item record
AbstractMost highly efficient perovskite solar cells employ mixed iodide–bromide photoactive layers; however, understanding the beneficial effect of the low (5–15 mol %) bromide content is incomplete. Here, a series of MAPb(I1–xBrx)3 perovskite layers are investigated to understand the origin of the high peak power conversion efficiency (19.2%) observed at small bromide content (0.10 ≤ x ≤ 0.125). For the x = 0.125 perovskite, 200 meV shallower energy levels are revealed, accompanied by a reduced density of trap states and stable tetragonal mixed-halide phase with compressed unit cell. In contrast, the higher bromide content samples (x > 0.125) show deeper energy levels, cubic perovskite crystal structure, and signs of halide segregation. Surface photovoltage measurements unveil an undesirable band bending at the hole transport layer/perovskite interface for MAPbI3 and x > 0.125 mixed-halide layers, which is eliminated for the x = 0.125 perovskite because of its shallower Fermi level, enabling enhanced device performance.
CitationDaboczi, M., Ratnasingham, S. R., Mohan, L., Pu, C., Hamilton, I., Chin, Y.-C., … Kim, J.-S. (2021). Optimal Interfacial Band Bending Achieved by Fine Energy Level Tuning in Mixed-Halide Perovskite Solar Cells. ACS Energy Letters, 3970–3981. doi:10.1021/acsenergylett.1c02044
SponsorsThe authors acknowledge the funding of UK Engineering and Physical Sciences Research Council (EPSRC) Plastic Electronics Doctoral Training Centre (EP/L016702/1) and KP Technology Ltd for EPSRC CASE studentships. This research was also supported by the UK EPSRC ATIP Programme Grant (EP/T028513/1) and the Global Research Laboratory Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017K1A1A2 013153).
PublisherAmerican Chemical Society (ACS)
JournalACS Energy Letters