<p>Sb<sub>2</sub>Se<sub>3 </sub>has emerged as an important photoelectrochemical (PEC) and photovoltaic (PV) material due to its rapid rise in photoconversion efficiencies. However, despite its binary nature, Sb<sub>2</sub>Se<sub>3 </sub>has a complex defect chemistry, which reduces the maximum photovoltage that can be obtained. Thus, it is important to understand these defects and to develop passivation strategies in order to further improve this material. In this work, a comprehensive investigation of the charge carrier dynamics of Sb<sub>2</sub>Se<sub>3</sub> and the influence of sulfur treatment on its optoelectronic properties was performed using time resolved microwave conductivity (TRMC), photoluminescence (PL) spectroscopy and low frequency Raman spectroscopy (LFRS). The key finding in this work is that upon sulfur treatment of Sb<sub>2</sub>Se<sub>3</sub>, the carrier lifetime is increased by the passivation of deep defects in Sb<sub>2</sub>Se<sub>3</sub> in both the surface region and the bulk, which is evidenced by increased charge carrier lifetime of TRMC decay dynamics, increased radiative recombination efficiency and decreased deep defect level emission (PL), and improved long-range order in the material (LFRS). These findings provide crucial insights into the defect passivation mechanisms in Sb<sub>2</sub>Se<sub>3</sub> paving the way for developing highly efficient PEC and PV devices.</p>
[M(nn)(dhn)] (where M is Pd(II) or Pt(II), nn is 2,2′-bipyridine, 1,10-phenanthroline, 2,2′-biquinoline, or 4,7-diphenyl-1,10-phenanthroline, and dhn is dianion of 2,3-naphthalenediol) photooxidizes the 2,2,6,6-tetramethyl-4-piperidinol in N,N dimethylformamide via 1O2 when irradiated with light of wave-lengths of 420 to 800 nm in presence of molecular oxygen. The presence of 1O2 as an intermediate is confirmed by quenching studies using bis(dibutyldithiocarbamato)nickel(II) and 20% water in DMF. The relative efficiency of 1O2 production sensitized by the above complexes depends on nature of metal, ligand, and geometry of the complexes. However, [Pd(bpy)(dmt)] and [Pd(phen)(dmt)] undergo photooxidation via 1O2 when sensitized by hematoporphyrin IX and its metal derivatives on photolysis under similar conditions. The relative efficiency of 1O2 production depends on the nature of metal in porphyrin.
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