Format

Send to

Choose Destination
Adv Mater. 2017 Oct;29(38). doi: 10.1002/adma.201702005. Epub 2017 Aug 18.

Globularity-Selected Large Molecules for a New Generation of Multication Perovskites.

Author information

1
École Polytechnique Fédérale de Lausanne, Laboratory of Photomolecular Science, Station 6, CH-1015, Lausanne, Switzerland.
2
Department of Physics, Alzahra University, Tehran, 1993891176, Iran.
3
Benemérita Universidad Autónoma de Puebla, CIDS, Av. San Claudio y 18 Sur, Col. San Manuel, Ciudad Universitaria, CP 72570, P.O. Box 1067, Puebla, Pue., 7200, Mexico.
4
Department of Nanotechnology and Advanced Materials, Materials and Energy Research Centre, Karaj, 31787-316, Iran.
5
École Polytechnique Fédérale de Lausanne, Laboratory for Photonics and Interfaces, 1015 Lausanne, Switzerland.
6
Department of Physics, Sharif University of Technology, Tehran, 14588, Iran.
7
Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, 14588, Iran.
8
Adolphe-Merkle-Institute, University of Fribourg Ch. du. Musée 3, CH-1700, Fribourg, Switzerland.
9
Computational Laboratory of Hybrid/Organic Photovoltaics (CLHYO), CNR-ISTM, via Elce di Sotto 8, I-06123, Perugia, Italy.
10
CompuNet, Istituto Italiano di Tecnologia, Via Morego 30, 16163, Genova, Italy.

Abstract

Perovskite solar cells (PSCs) use perovskites with an APbX3 structure, where A is a monovalent cation and X is a halide such as Cl, Br, and/or I. Currently, the cations for high-efficiency PSCs are Rb, Cs, methylammonium (MA), and/or formamidinium (FA). Molecules larger than FA, such as ethylammonium (EA), guanidinium (GA), and imidazolium (IA), are usually incompatible with photoactive "black"-phase perovskites. Here, novel molecular descriptors for larger molecular cations are introduced using a "globularity factor", i.e., the discrepancy of the molecular shape and an ideal sphere. These cationic radii differ significantly from previous reports, showing that especially ethylammonium (EA) is only slightly larger than FA. This makes EA a suitable candidate for multication 3D perovskites that have potential for unexpected and beneficial properties (suppressing halide segregation, stability). This approach is tested experimentally showing that surprisingly large quantities of EA get incorporated, in contrast to most previous reports where only small quantities of larger molecular cations can be tolerated as "additives". MA/EA perovskites are characterized experimentally with a band gap ranging from 1.59 to 2.78 eV, demonstrating some of the most blue-shifted PSCs reported to date. Furthermore, one of the compositions, MA0.5 EA0.5 PbBr3 , shows an open circuit voltage of 1.58 V, which is the highest to date with a conventional PSC architecture.

KEYWORDS:

light-emitting devices; perovskite solar cells; quasi-3D cations; wide band-gap semiconductors

PMID:
28833614
DOI:
10.1002/adma.201702005

Supplemental Content

Full text links

Icon for Wiley
Loading ...
Support Center