Summary of different photophysical properties of the sTTA-UC system comprised of [Os(bpy)₃]²⁺ and DCA in different solvents^a.

Solvent	k TTET/M−1 s−1	k TTA/M−1 s−1	[DCA]/mM	λ ex/nm	Φ sTTA-UC b/%	ΔEb/eV
Acetonitrile	4 × 109	6.9 × 109	0.5	635	∼0.22	0.88
				705	∼0.10	1.06
Acetone	4 × 109	6.4 × 109	0.5	635	∼0.13	0.88
				705	∼0.15	1.08
Dichloromethane	3 × 109	6.7 × 109	3	635	∼1.5	0.73
				705	∼1.4	0.92

^aThe data were recorded in de-aerated solvents. Details for the determination of the triplet–triplet energy transfer rate constant k_TTET, the triplet–triplet annihilation rate constant k_TTA, the sensitized triplet–triplet annihilation upconversion quantum yield Φ_sTTA-UC and the apparent pseudo anti-Stokes shifts ΔE are in the ESI in Sections 4.2 and 4.3.

^bThe pseudo anti-Stokes shift and the upconversion quantum yield were determined using the concentrations of DCA indicated in the table. The concentration of [Os(bpy)₃](PF₆)₂ was different for excitation with a 635 nm cw laser (20 μM) and a 705 nm cw laser excitation (50 μM).