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In-gap states in solar cell absorbers that are recombination centers determine the cell's photovoltaic performance. Using scanning tunneling spectroscopy (STS), temperature-dependent photoconductivity and steady-state photocarrier-grating measurements we probed, directly and indirectly, the energies of such states, both at the surface and in the bulk of two similar, but different halide perovskites, the single cation MAPbI (here MAPI) and the mixed cation halide perovskite, FAMACsPb(IBr) (here MCHP). We found a correlation between the energy distribution of the in-gap states, as determined by STS measurements, and their manifestation in the photo-transport parameters of the MCHP absorbers. In particular, our results suggest that the in-gap recombination centers in the MCHP are shallower than those of MAPI. This can be one explanation for the better photovoltaic efficiency of the former.
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http://dx.doi.org/10.1039/c8cp03555e | DOI Listing |
Phys Rev Lett
August 2025
Shanghai Jiao Tong University, Tsung-Dao Lee Institute, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai 200240, China.
While Andreev bound states (ABSs) have been realized in engineered superconducting junctions, their direct observation in normal metal-superconductor heterostructures-enabled by quantum confinement-remains experimentally elusive. Here, we report the detection of ABSs in ultrathin metallic islands (Bi, Ag, and SnTe) grown on the s-wave superconductor NbN. Using high-resolution scanning tunneling microscopy and spectroscopy, we clearly reveal in-gap ABSs with energies symmetric about the Fermi level.
View Article and Find Full Text PDFACS Nano
September 2025
Department of Physics, University of Texas at Austin, Austin, Texas 78712, United States.
Atomic point defects provide an alternative tuning knob for engineering the properties and functionality of 2D transition metal dichalcogenides (TMDs). Prior to engineering point defects to tailor material properties, identification and investigation of their electronic structure is key to their implementation for device applications. The two most common atomic point defects in monolayer WS are sulfur vacancies and oxygen substituents, which have been thoroughly reported on, but their interaction has yet to be investigated.
View Article and Find Full Text PDFBrain Sci
July 2025
School of Communication Sciences and Disorders, University of Memphis, Memphis, TN 38152, USA.
Understanding the origin and natural organization of early infant vocalizations is important for predicting communication and language abilities in later years. The very frequent production of speech-like vocalizations (hereafter "protophones"), occurring largely independently of interaction, is part of this developmental process. This study aims to investigate the gap durations (time intervals) between protophones, comparing typically developing (TD) infants and infants later diagnosed with autism spectrum disorder (ASD) in a naturalistic setting where endogenous protophones occur frequently.
View Article and Find Full Text PDFJ Phys Condens Matter
September 2025
Department of Physics, Kent State University, Kent, OH 44242, United States of America.
We revisit certain aspects of a problem concerning the influence of carrier scattering induced by magnetic impurities in metals on their superconducting properties. Superconductivity is assumed to be driven by strong electron-phonon interaction. We use the self-consistent solution of the Nagaoka equations for the scattering matrix together with the Migdal-Eliashberg theory of superconductivity to compute the energy of the in-gap bound states, superconducting critical temperature and tunneling density of states for a wide range of values of the Kondo temperature and impurity concentrations.
View Article and Find Full Text PDFACS Nanosci Au
August 2025
Graduate School of Advanced Technology, National Taiwan University, Taipei 106319, Taiwan.
This study investigates the photocatalytic performance of CuO surfaces modified with halogen-substituted phenylacetylenes (4-XA), including 1-ethynyl-4-fluorobenzene (4-FA), 1-chloro-4-ethynylbenzene (4-CA), and 1-bromo-4-ethynylbenzene (4-BA), using an integrated theoretical and experimental approach. Through density functional theory (DFT) calculations and ultraviolet photoelectron spectroscopy (UPS) measurements, we analyze how these molecular decorators affect charge transfer dynamics and the electronic structure of the CuO {100}, {110}, and {111} facets. Two distinct photocatalytic mechanisms are proposed: one where electrons reach the vacuum level through the molecular decorator and another where electrons escape directly through the CuO surface via molecular-induced hybridized states.
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