Premium
Understanding the Role of Grain Boundaries on Charge‐Carrier and Ion Transport in Cs 2 AgBiBr 6 Thin Films
Author(s) -
Li Zewei,
Senanayak Satyaprasad P.,
Dai Linjie,
Kusch Gunnar,
Shivanna Ravichandran,
Zhang Youcheng,
Pradhan Dipika,
Ye Junzhi,
Huang YiTeng,
Sirringhaus Henning,
Oliver Rachel A.,
Greenham Neil C.,
Friend Richard H.,
Hoye Robert L. Z.
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202104981
Subject(s) - materials science , grain boundary , perovskite (structure) , thin film , charge carrier , diffusion , semiconductor , cathodoluminescence , optoelectronics , grain size , chemical physics , nanotechnology , crystallography , microstructure , composite material , thermodynamics , chemistry , physics , luminescence
Abstract Halide double perovskites have gained significant attention, owing to their composition of low‐toxicity elements, stability in air, and recent demonstrations of long charge‐carrier lifetimes that can exceed 1 µs. In particular, Cs 2 AgBiBr 6 is the subject of many investigations in photovoltaic devices. However, the efficiencies of solar cells based on this double perovskite are still far from the theoretical efficiency limit of the material. Here, the role of grain size on the optoelectronic properties of Cs 2 AgBiBr 6 thin films is investigated. It is shown through cathodoluminescence measurements that grain boundaries are the dominant nonradiative recombination sites. It also demonstrates through field‐effect transistor and temperature‐dependent transient current measurements that grain boundaries act as the main channels for ion transport. Interestingly, a positive correlation between carrier mobility and temperature is found, which resembles the hopping mechanism often seen in organic semiconductors. These findings explain the discrepancy between the long diffusion lengths >1 µm found in Cs 2 AgBiBr 6 single crystals versus the limited performance achieved in their thin film counterparts. This work shows that mitigating the impact of grain boundaries will be critical for these double perovskite thin films to reach the performance achievable based on their intrinsic single‐crystal properties.