Photodoping through local charge carrier accumulation in alloyed hybrid perovskites for highly efficient luminescence

• Published in: Nature photonics Vol. 14; no. 2; pp. 123 - 128
• Main Authors: Feldmann, Sascha, Macpherson, Stuart, Senanayak, Satyaprasad P., Abdi-Jalebi, Mojtaba, Rivett, Jasmine P. H., Nan, Guangjun, Tainter, Gregory D., Doherty, Tiarnan A. S., Frohna, Kyle, Ringe, Emilie, Friend, Richard H., Sirringhaus, Henning, Saliba, Michael, Beljonne, David, Stranks, Samuel D., Deschler, Felix
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-02-2020; Nature Publishing Group
• Subjects: 140/125; 639/301/1005; 639/301/299/946; 639/638/440/527; Accumulation; Alloying; Applied and Technical Physics; Carrier density; Carrier recombination; Cations; Charge injection; Current carriers; Diodes; Electron states; First principles; Light emission; Light emitting diodes; Luminescence; Mapping; Metal halides; Optoelectronic devices; Organic light emitting diodes; Perovskites; Photovoltaic cells; Physics; Physics and Astronomy; Quantum Physics; Recombination; Solar cells; Spectroscopy
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-019-0546-8

Metal halide perovskites have emerged as exceptional semiconductors for optoelectronic applications. Substitution of the monovalent cations has advanced luminescence yields and device efficiencies. Here, we control the cation alloying to enhance optoelectronic performance through alteration of the charge carrier dynamics in mixed-halide perovskites. In contrast to single-halide perovskites, we find high luminescence yields for photoexcited carrier densities far below solar illumination conditions. Using time-resolved spectroscopy we show that the charge carrier recombination regime changes from second to first order within the first tens of nanoseconds after excitation. Supported by microscale mapping of the optical bandgap, electrically gated transport measurements and first-principles calculations, we demonstrate that spatially varying energetic disorder in the electronic states causes local charge accumulation, creating p- and n-type photodoped regions, which unearths a strategy for efficient light emission at low charge-injection in solar cells and light-emitting diodes.
Localized photodoping in mixed-cation perovskites is shown to modify charge-carrier recombination and thus offer a route for more efficient light emission.