Maximizing the optical performance of planar CH3NH3PbI3 hybrid perovskite heterojunction stacks

Phillips, LJ ORCID: 0000-0001-5181-1565, Rashed, AM, Treharne, RE, Kay, J, Yates, P, Mitrovic, IZ ORCID: 0000-0003-4816-8905, Weerakkody, A, Hall, S ORCID: 0000-0001-8387-1036 and Durose, K ORCID: 0000-0003-1183-3211 (2016) Maximizing the optical performance of planar CH3NH3PbI3 hybrid perovskite heterojunction stacks. Solar Energy Materials and Solar Cells, 147. pp. 327-333.

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Abstract

A vapour-phase reaction process has been used to deposit smooth and uniform CH3NH3PbI3 perovskite material to enable the measurement of its optical dispersion relations, n and k, by ellipsometry. Fitting was achieved with a combination of Tauc-Lorenz, critical point parabolic band (CPPB) and harmonic oscillators. We have used the dispersion relations in an all-optical model of new planar device architectures in order to establish design rules for future materials choices to maximize the short-circuit current (Jsc) performance. For 500nm of MAPI with no window layer, the maximum performance expected from the model is Jsc=21.63mAcm-2. The ability of thin layers (in the range 20-60nm) of a range of window layer materials (TiO2, WO3, ZnO, Nb2O5, CdS, and Cd0.4 Zn0.6S) to enhance the short-circuit current of the devices was investigated. The performance of the oxides showed interference behaviour, with the first maxima in their J sc curves exceeding the value achievable without a window layer. However, after the first maximum, the performance generally fell off with increasing thickness. The only material to stay greater than the no-window condition for the entire investigated range is WO3. The highest performance (J sc of 22.47mAcm-2) was obtained with 59nm of WO3, with that of TiO2, ZnO, and Nb2O5 being marginally lower. Parasitic absorption in CdS window layers caused the J sc to decrease for all non-zero thicknesses - it gives no interference enhancement and its use cannot be recommended on optical grounds. Use of the wider gap alloy Cd0.4Zn0.6S gave higher currents than did CdS but its performance was not so high as for the oxides. Observations are made on the practicalities of fabricating the target structures in the fabrication of practical PV devices.

Item Type:	Article
Uncontrolled Keywords:	Solar, Perovskite, CH3NH3PbI3, Optical properties, Ellipsometry, Dispersion relations
Depositing User:	Symplectic Admin
Date Deposited:	07 Feb 2017 15:25
Last Modified:	19 Jan 2023 07:19
DOI:	10.1016/j.solmat.2015.10.007
Related URLs:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3005595

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• Maximizing the optical performance of planar CH3NH3PbI3 hybrid perovskite heterojunction stacks. (deposited 06 Feb 2017 09:14)
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