Abstract
Two-dimensional (2D) halide perovskites have great promise in optoelectronic devices because of their stability and optical tunability, but the subtle effects on the inorganic layer when modifying the organic spacer remain unclear. Here, we introduce two homologous series of Ruddlesden-Popper (RP) structures using the branched isobutylammonium (IBA) and isoamylammonium (IAA) cations with the general formula (RA)2(MA)n-1PbnI3n+1 (RA = IBA, IAA; MA = methylammonium n = 1-4). Surprisingly, the IAA n = 2 member results in the first modulated 2D perovskite structure with a ripple with a periodicity of 50.6 Å occurring in the inorganic slab diagonally to the [101] direction of the basic unit cell. This leads to an increase of Pb-I-Pb angles along the direction of the wave. Generally, both series show larger in-plane bond angles resulting from the additional bulkiness of the spacers compensating for the MA's small size. Larger bond angles have been shown to decrease the bandgap which is seen here with the bulkier IBA leading to both larger in-plane angles and lower bandgaps except for n = 2, in which the modulated structure has a lower bandgap because of its larger Pb-I-Pb angles. Photo-response was tested for the n = 4 compounds and confirmed, signaling their potential use in solar cell devices. We made films using an MACl additive which showed good crystallinity and preferred orientation according to grazing-incidence wide-angle scattering (GIWAXS). As exemplar, the two n = 4 samples were employed in devices with champion efficiencies of 8.22% and 7.32% for IBA and IAA, respectively.
Original language | English (US) |
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Pages (from-to) | 12139-12148 |
Number of pages | 10 |
Journal | Chemical Science |
Volume | 11 |
Issue number | 44 |
DOIs | |
State | Published - Nov 28 2020 |
ASJC Scopus subject areas
- Chemistry(all)
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CCDC 2018080: Experimental Crystal Structure Determination
Hoffman, J. M. (Contributor), Malliakas, C. D. (Contributor), Sidhik, S. (Contributor), Hadar, I. (Contributor), Mcclain, R. (Contributor), Mohite, A. D. (Contributor), Kanatzidis, M. (Contributor) & Kanatzidis, M. G. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc25qzc8, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc25qzc8&sid=DataCite
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CCDC 2018082: Experimental Crystal Structure Determination
Hoffman, J. M. (Contributor), Malliakas, C. D. (Contributor), Sidhik, S. (Contributor), Hadar, I. (Contributor), Mcclain, R. (Contributor), Mohite, A. D. (Contributor), Kanatzidis, M. (Contributor) & Kanatzidis, M. G. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc25qzfb, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc25qzfb&sid=DataCite
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CCDC 2018087: Experimental Crystal Structure Determination
Hoffman, J. M. (Contributor), Malliakas, C. D. (Contributor), Sidhik, S. (Contributor), Hadar, I. (Contributor), Mcclain, R. (Contributor), Mohite, A. D. (Contributor), Kanatzidis, M. (Contributor) & Kanatzidis, M. G. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc25qzlh, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc25qzlh&sid=DataCite
Dataset