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Maximizing and stabilizing luminescence from halide perovskites with potassium passivation

DOI: 10.1038/nature25989 DOI Help

Authors: Mojtaba Abdi-jalebi (University of Cambridge) , Zahra Andaji-garmaroudi (University of Cambridge) , Stefania Cacovich (University of Cambridge) , Camille Stavrakas (University of Cambridge) , Bertrand Philippe (Uppsala University) , Johannes M. Richter (University of Cambridge) , Mejd Alsari (University of Cambridge) , Edward P. Booker (University of Cambridge) , Eline M. Hutter (Delft University of Technology) , Andrew J. Pearson (University of Cambridge) , Samuele Lilliu (University of Sheffield; The UAE Centre for Crystallography) , Tom J. Savenije (Delft University of Technology) , Hakan Rensmo (Uppsala University) , Giorgio Divitini (University of Cambridge) , Caterina Ducati (University of Cambridge) , Richard H. Friend (University of Cambridge) , Samuel D. Stranks (University of Cambridge)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature , VOL 555 , PAGES 497 - 501

State: Published (Approved)
Published: March 2018
Diamond Proposal Number(s): 15841

Abstract: Metal halide perovskites are of great interest for various high-performance optoelectronic applications. The ability to tune the perovskite bandgap continuously by modifying the chemical composition opens up applications for perovskites as coloured emitters, in building-integrated photovoltaics, and as components of tandem photovoltaics to increase the power conversion efficiency. Nevertheless, performance is limited by non-radiative losses, with luminescence yields in state-of-the-art perovskite solar cells still far from 100 per cent under standard solar illumination conditions. Furthermore, in mixed halide perovskite systems designed for continuous bandgap tunability (bandgaps of approximately 1.7 to 1.9 electronvolts), photoinduced ion segregation leads to bandgap instabilities. Here we demonstrate substantial mitigation of both non-radiative losses and photoinduced ion migration in perovskite films and interfaces by decorating the surfaces and grain boundaries with passivating potassium halide layers. We demonstrate external photoluminescence quantum yields of 66 per cent, which translate to internal yields that exceed 95 per cent. The high luminescence yields are achieved while maintaining high mobilities of more than 40 square centimetres per volt per second, providing the elusive combination of both high luminescence and excellent charge transport. When interfaced with electrodes in a solar cell device stack, the external luminescence yield—a quantity that must be maximized to obtain high efficiency—remains as high as 15 per cent, indicating very clean interfaces. We also demonstrate the inhibition of transient photoinduced ion-migration processes across a wide range of mixed halide perovskite bandgaps in materials that exhibit bandgap instabilities when unpassivated. We validate these results in fully operating solar cells. Our work represents an important advance in the construction of tunable metal halide perovskite films and interfaces that can approach the efficiency limits in tandem solar cells, coloured-light-emitting diodes and other optoelectronic applications.

Journal Keywords: Devices for energy harvesting; Fluorescence spectroscopy; Solar cells

Subject Areas: Materials, Physics, Energy


Instruments: I09-Surface and Interface Structural Analysis

Other Facilities: European Synchrotron Radiation Facility