Unraveling the compositional heterogeneity and carrier dynamics of alkali cation doped 3D/2D perovskites with improved stability
Ming Chun Tang, Siyuan Zhang, Nhan V. Nguyen, Edwin J. Heilweil, Christina A. Hacker, Timothy J. Magnanelli, Thomas D. Anthopoulos
Preventing the degradation of hybrid perovskite by humid air remains a challenge for their future commercial utilization. 3D/2D perovskites with hierarchical architecture have attracted significant attention due to their promising power conversion efficiency (PCE) and device stability. Here, a novel 3D/2D planar bi-layer perovskite obtained by growing 2D Ruddlesden– Popper capping layer on top of 3D rubidium (Rb+)-doped mixed-cation perovskite is developed. It is found that Rb+ cation incorporation decreases the work function of 3D films, and 3D/2D hybrid films show smaller work function values compared to their classic 3D perovskites. X-ray photoemission spectroscopy confirms the presence of a 2D perovskite capping layer and observes a halide migration from 3D to the 2D perovskite layer. Time-resolved terahertz spectroscopy shows that the 2D layer has a limited impact on the carrier dynamics of 3D/2D double layers. The average DC carrier mobility for 3D/2D hierarchical structures, as well as their 3D counterparts, is one order of magnitude higher than the 2D perovskite. The resulting 3D/2D Rb+-incorporated perovskite solar cells show a peak PCE of over 20%, which is slightly higher than their 3D counterpart (19.5%). Benefited from the moisture resistivity, the 3D/2D perovskite photovoltaics show significantly improved long-term stability by retaining 81% of the initial PCE after 60 days of exposure in ambient air (50 ± 10% relative humidity) without encapsulation. In all, this study provides new insights into structural and interfacial properties, carrier dynamics, and their effects on device performance of the 3D/2D perovskite solar cells with improved stability.
, Zhang, S.
, Nguyen, N.
, Heilweil, E.
, Hacker, C.
, Magnanelli, T.
and Anthopoulos, T.
Unraveling the compositional heterogeneity and carrier dynamics of alkali cation doped 3D/2D perovskites with improved stability, Materials Advances, [online], https://dx.doi.org/10.1039/D0MA00967A, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=931083
(Accessed May 12, 2021)