Lead halide perovskite quantum dots (QDs) possess color-tunable and narrow-band emissions and are very promising for lighting and display applications, but they suffer from lead toxicity and instability. Although lead-free Bi-based and Sn-based perovskite QDs (CsSnX3, Cs2SnX6 and (CH3NH3)3Bi2X9) have been reported, they all showed low photoluminescence quantum yield (PLQY) and poor stability. Here we report the synthesis of Cs3Bi2Br9 perovskite QDs with high PLQY and excellent stability. Via a green and facile process using ethanol as the anti-solvent, as-synthesized Cs3Bi2Br9 QDs show a blue emission at 410 nm with a PLQY up to 19.4%. The whole series of Cs3Bi2X9 (X = Cl, Br, I) QDs by mixing precursors could cover the PL emission range from 393 to 545 nm. Furthermore, Cs3Bi2Br9 QDs show excellent photostability and moisture stability due to the all-inorganic nature and the surface passivation by BiOBr, which enables the one-pot This article is protected by copyright. All rights reserved. 3 synthesis of Cs3Bi2Br9 QDs/silica composite. A lead-free perovskite white light emitting diode (W-LED) is fabricated by simply combine the composite of Cs3Bi2Br9 QDs/silica with Y3Al5O12 (YAG) phosphor. As a new member of lead-free perovskite QDs, Cs3Bi2Br9 QDs open up a new route for the fabrication of optoelectronic devices due to their excellent stability and photophysical characteristics.

Lead halide perovskite quantum dots (QDs) are promising candidates for future lighting applications, due to their high quantum yield, narrow full width at half maximum (FWHM), and wide color gamut. However, the toxicity of lead represents a potential obstacle to their utilization. Although tin(II) has been used to replace lead in films and QDs, the high intrinsic defect density and oxidation vulnerability typically leads to unsatisfactory material properties. Bismuth, with much lower toxicity than lead, is promising to constitute lead-free perovskite materials because Bi is isoelectronic to Pb and more stable than Sn . Herein we report, for the first time, the synthesis and optical characterization of MA Bi Br perovskite QDs with photoluminescence quantum yield (PLQY) up to 12 %, which is much higher than Sn-based perovskite nanocrystals. Furthermore, the photoluminescence (PL) peaks of MA Bi X QDs could be easily tuned from 360 to 540 nm through anion exchange.

Photodetectors convert light signals into current or voltage outputs and are widely used for imaging, sensing, and spectroscopy. Perovskite-based photodetectors have shown high sensitivity and fast response due to the unprecedented low recombination loss in this solution processed semiconductor. Among various types of CHNHPbI morphology (film, single crystal, nanowire), single-crystalline CHNHPbI nanowires are particularly interesting for photodetection because of their reduced grain boundary, morphological anisotropy, and excellent mechanical flexibility. The concomitant disadvantage associated with the CHNHPbI nanowire photodetectors is their large surface area, which catalyzes carrier recombination and material decomposition, thus significantly degrading device performance and stability. Here we solved this key problem by introducing oleic acid soaking to passivate surface defects of CHNHPbI nanowires, which leads to a device with much improved stability and unprecedented sensitivity (measured detectivity of 2 × 10 Jones). By taking advantage of their one-dimensional geometry, we also showcased, for the first time, the linear dichroic photodetection of our CHNHPbI nanowire photodetector.