Open AccessIn Operando, Photovoltaic, and Microscopic Evaluation of Recombination Centers in Halide Perovskite-Based Solar Cells
Author(s) -
Arava Zohar,
Michael Kulbak,
SilverHamill TurrenCruz,
Pabitra K. Nayak,
Adi Kama,
Anders Hagfeldt,
Henry J. Snaith,
Gary Hodes,
David Cahen
Publication year - 2021
Publication title -
acs applied materials and interfaces
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.535
H-Index - 228
eISSN - 1944-8252
pISSN - 1944-8244
DOI - 10.1021/acsami.1c08675
Subject(s) - materials science , electron beam induced current , perovskite (structure) , optoelectronics , photovoltaics , halide , electric field , photovoltaic system , carrier lifetime , diffusion , grain boundary , solar cell , charge carrier , recombination , silicon , crystallography , microstructure , chemistry , physics , inorganic chemistry , ecology , biochemistry , quantum mechanics , gene , biology , thermodynamics , metallurgy
The origin of the low densities of electrically active defects in Pb halide perovskite (HaP), a crucial factor for their use in photovoltaics, light emission, and radiation detection, remains a matter of discussion, in part because of the difficulty in determining these densities. Here, we present a powerful approach to assess the defect densities, based on electric field mapping in working HaP-based solar cells. The minority carrier diffusion lengths were deduced from the electric field profile, measured by electron beam-induced current (EBIC). The EBIC method was used earlier to get the first direct evidence for the n-i-p junction structure, at the heart of efficient HaP-based PV cells, and later by us and others for further HaP studies. This manuscript includes EBIC results on illuminated cell cross sections (in operando) at several light intensities to compare optoelectronic characteristics of different cells made by different groups in several laboratories. We then apply a simple, effective single-level defect model that allows deriving the densities ( N r ) of the defect acting as recombination center. We find N r ≈ 1 × 10 13 cm -3 for mixed A cation lead bromide-based HaP films and ∼1 × 10 14 cm -3 for MAPbBr 3 (Cl). As EBIC photocurrents are similar at the grain bulk and boundaries, we suggest that the defects are at the interfaces with selective contacts rather than in the HaP film. These results are relevant for photovoltaic devices as the EBIC responses distinguish clearly between high- and low-efficiency devices. The most efficient devices have n-i-p structures with a close-to-intrinsic HaP film, and the selective contacts then dictate the electric field strength throughout the HaP absorber.