(color online) Comparison of iodide-, chloride-, and bromide-treated CQD solids and corresponding devices. (a) Three devices performance tested in air; EQE of iodide (b) and bromide (c) solid-state ligand-exchanged devices observed before and after air exposure; (d) Fermi level ( , valence band ( , and conduction band level ( of CQD films with different halide treatments; (e) the amounts of oxidized species in CQD films with different halide treatments.^[123]