Colloidal lead halide
perovskite nanocrystals (NCs) have recently
emerged as versatile photonic sources. Their processing and optoelectronic
applications are hampered by the loss of colloidal stability and structural
integrity due to the facile desorption of surface capping molecules
during isolation and purification. To address this issue, herein,
we propose a new ligand capping strategy utilizing common and inexpensive
long-chain zwitterionic molecules such as 3-(N,N-dimethyloctadecylammonio)propanesulfonate, resulting in
much improved chemical durability. In particular, this class of ligands
allows for the isolation of clean NCs with high photoluminescence
quantum yields (PL QYs) of above 90% after four rounds of precipitation/redispersion
along with much higher overall reaction yields of uniform and colloidal
dispersible NCs. Densely packed films of these NCs exhibit high PL
QY values and effective charge transport. Consequently, they exhibit
photoconductivity and low thresholds for amplified spontaneous emission
of 2 μJ cm–2 under femtosecond optical excitation
and are suited for efficient light-emitting diodes.
Photodegradation processes play an important role in releasing elements tied up in biologically refractory forms in the environment, and are increasingly recognized as important contributors to biogeochemical cycles. While complete photooxidation of dissolved organic carbon (to CO 2), and dissolved organic phosphorous (to PO 4 3-) has been documented, the analogous photoproduction of sulfate from dissolved organic sulfur (DOS) has not yet been reported. Recent high-resolution mass spectrometry studies showed a selective loss of organic sulfur during photodegradation of dissolved organic matter, which was hypothesized to result in the production of sulfate. Here, we provide evidence of ubiquitous production of sulfate, methanesulfonic acid (MSA) and methanesulfinic acid (MSIA) during photodegradation of
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