Redox-mediated reversible modulation of the photoluminescence of single quantum dots

Li Ying^a), Liu Ren-Wei^a),^b), Ma Li^a), Fan Su-Na^a),^b), Li Hui^a), Hu Shu-Xin†^a), Li Ming^a)

Positions of the energy levels of the conduction band (CB) and the valence band (VB) of the CdSe and QD655 (CdSe/ZnS), the redox peaks of BME in its original and two oxidized states, i.e., OX₁ and OX₂ along with that of the [Fe(CN)₆]^4−/3− compound which is often used as the standard in electrochemical studies. The redox peaks Fe^2+/3+ are also shown for reference. (b)–(d) Schematic illustration of possible ET pathways between a QD and BME in different oxidation states. The solid blue arrows show the possible electron transfer pathway. The dotted silver arrows show the possible hole transfer pathway. (b) The filling of surface trap states of the QD by the electrons from BME. (c) Electron transfer from the CB of the QD to the unoccupied electron level of OX₁. (d) The ET process between OX₂ and the hole traps.