Available on-demand - F.MT02.05.03
Correlative Imaging of the Local Optoelectronic Properties within Single and Multijunction Halide Perovskite Solar Cells
Elizabeth Tennyson1,Kyle Frohna1,William Drake1,Florent Sahli2,Quentin Jeangros2,Christophe Ballif2,Samuel Stranks1
University of Cambridge1,École Polytechnique Fédérale de Lausanne, Photovoltaics and Thin-Film Electronics Laboratory2
The functional properties of halide perovskite semiconductors at the micro and nanoscales are heterogeneous,1 and there is a pressing need to understand how these properties (electrical, chemical, etc.) influence one another and affect overall photovoltaic (PV) performance. In this presentation, we begin by showing a variety of correlative microscopy methods that have been applied to perovskite solar cells to investigate the local electrical, chemical, and optical properties of single-junction devices.2–4 For this, Kelvin probe force microscopy, nano-IR imaging, time-of-flight secondary ion mass spectroscopy depth profiling among other characterization techniques were implemented. These results reveal that the perovskite’s (i) nanoscale voltage response depends on its chemical composition (ii) charge carrier dynamics depend on the incident photon energy (i.e. wavelength), and (iii) altered chemical properties due to the inclusion of potassium additives impact the electrical response in three dimensions.
Beyond single-junction perovskite PV, and a promising real-world application for this material class, is the multi-junction perovskite/c-Si solar cell. Not only are perovskites complex on their own, but when embedded within a textured heterojunction, the interactions between device architecture and material performance introduces new challenges. Commercial c-Si solar cells are etched to form micro-scale, randomly distributed pyramids on their front side, complicating the growth of the perovskite top cell. It is not well understood how the local light-matter interactions of the perovskite material behave when incorporated into this type of multijunction architecture. Therefore, we present optoelectronic microscopy measurements correlated with optical simulations of perovskite on textured c-Si solar cells. Through wide-field, hyperspectral photoluminescence (PL) imaging, we measure the photon out-coupling of the perovskite material and find both a spectral and spatial dependence on the geometrical patterning which dominates any grain-to-grain variation that is typically found in perovskite PL measurements.5 Such heterogeneity reveals the importance of the underlying c-Si texture design, suggesting that tuning the surface morphology could lead to a homogenization of the perovskite’s PL emission, which may boost the multi-junction solar cell efficiency.
(1) Tennyson, E. M.; Doherty, T. A. S.; Stranks, S. D. Heterogeneity at Multiple Length Scales in Halide Perovskite Semiconductors. Nat Rev Mater 2019, 4 (9), 573–587 - invited review, front cover
(2) Tennyson, E. M.; Roose, B.; Garrett, J. L.; Gong, C.; Munday, J. N.; Abate, A.; Leite, M. S. Cesium-Incorporated Triple Cation Perovskites Deliver Fully Reversible and Stable Nanoscale Voltage Response. ACS Nano 2019, 13 (2), 1538–1546 - cover
(3) Tennyson, E. M.; Howard, J. M.; Roose, B.; Garrett, J. L.; Munday, J. N.; Abate, A.; Leite, M. S. The Effects of Incident Photon Energy on the Time-Dependent Voltage Response of Lead Halide Perovskites. Chem. Mater. 2019, 31 (21), 8969–8976 - front cover
(4) Tennyson, E. M.; Abdi-Jalebi, M.; Ji, K.; Garrett, J. L.; Gong, C.; Pawlicki, A., A.; Ovchinnikova, O., S.; Munday, J. N.; Stranks, S. D.; Leite, M. S. Correlated Electrical and Chemical Nanoscale Properties in Potassium-Passivated, Triple-Cation Perovskite Solar Cells. Adv. Mater. Inter. 2020 - in press
(5) Tennyson, E.M.; Frohna K.; Drake, W.K.; Sahli, F.; Yang, T. C.-Y.; Fu, F.; Werner, J.; Jeangros, Q.; Ballif, C.; Stranks, S.D. Multimodal Microscale Imaging of Textured Perovskite/c-Si Tandem Solar Cells - in preparation