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Negative Thermal Quenching and Size‐Dependent Optical Characteristics of Highly Luminescent Phosphorene Nanocrystals
Author(s) -
Jana Subhajit,
Mukherjee Subhrajit,
Ghorai Arup,
Bhaktha Shivakiran B. N.,
Ray Samit Kumar
Publication year - 2020
Publication title -
advanced optical materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.89
H-Index - 91
ISSN - 2195-1071
DOI - 10.1002/adom.202000180
Subject(s) - materials science , photoluminescence , luminescence , exfoliation joint , quenching (fluorescence) , absorption (acoustics) , nanocrystal , band gap , phosphorene , semiconductor , absorption edge , optoelectronics , direct and indirect band gaps , photodetection , analytical chemistry (journal) , nanotechnology , photodetector , graphene , optics , fluorescence , composite material , physics , chemistry , chromatography
Highly luminescent and direct band gap black phosphorus (BP) nanocrystals (NCs) synthesized using a cost‐effective sonochemical exfoliation route are reported. Microscopic studies have confirmed the exfoliation of few‐layer nanoflakes and BP NCs with variable average size between ≈2 and ≈8 nm. Structural and vibrational characteristics reveal the superior crystalline quality by retaining the phase and crystalline symmetry in NCs. Size‐dependent absorption characteristics are observed by controlling the nanoparticle size and show a progressive blue shift near band edge absorption on reducing the size, useful for selective multicolor photodetection. Temperature‐dependent photoluminescence measurements from room temperature (300 K) down to 10 K are performed. Most interestingly, BP NCs with the lowest diameter exhibit a novel negative thermal quenching behavior as compared to positive thermal quenching observed usually in bulk semiconductors and BP NCs with larger diameter. Metal–semiconductor–metal type (Au/BP‐NCs/Au) photodetectors are fabricated to study their photoresponse properties, which reveal the potential application of BP NCs as optical modulators.