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Defect-Assisted Photoinduced Halide Segregation in Mixed-Halide Perovskite Thin Films

DOI: 10.1021/acsenergylett.7b00282 DOI Help

Authors: Alex J. Barker (Istituto Italiano di Tecnologia) , Aditya Sadhanala (University of Cambridge) , Felix Deschler (University of Cambridge) , Marina Gandini (Istituto Italiano di Tecnologia) , Satyaprasad P. Senanayak (University of Cambridge) , Phoebe M. Pearce , Edoardo Mosconi (CNR-ISTM) , Andrew Pearson (University of Cambridge) , Yue Wu (University of Oxford) , Ajay Ram Srimath Kandada (Istituto Italiano di Tecnologia) , Tomas Leitjens (Istituto Italiano di Tecnologia) , Filippo De Angelis (CNR-ISTM; Computation, Istituto Italiano di Tecnologia) , Sian E. Dutton (University of Cambridge) , Annamaria Petrozza (Istituto Italiano di Tecnologia) , Richard H. Friend (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acs Energy Letters

State: Published (Approved)
Published: May 2017
Diamond Proposal Number(s): 11454 , 12436

Abstract: Solution processable lead halide perovskites show immense promise for use in photovoltaics and other optoelectronic applications. The ability to tune their bandgap by alloying various halide anions (for example in CH3NH3Pb(I1-xBrx)3, 0<x<1) is however hampered by the reversible photoinduced formation of sub-bandgap emissive states. We find that ion segregation takes place via halide defects, resulting in iodide-rich low-bandgap regions close to the illuminated surface of the film. This segregation may be driven by the strong gradient in carrier generation rate through the thickness of these strongly absorbing materials. Once returned to the dark, entropically-driven intermixing of halides returns the system to a homogeneous condition. We present approaches to supress this process by controlling either the internal light distribution or the defect density within the film. These results are relevant to stability in both single- and mixed-halide perovskites, leading the way towards tuneable and stable perovskite thin films for photovoltaic and light-emitting applications.

Subject Areas: Materials, Chemistry, Energy


Instruments: I07-Surface & interface diffraction , I12-JEEP: Joint Engineering, Environmental and Processing