Figure shows the steady-state absorption spectra of the investigated PbS QDs with first excitonic transitions at 1474 nm (PbS-A, Ø5.5 nm), 1526 nm (PbS-B, Ø6.8 nm), 1656 nm (PbS-C, Ø7.3 nm), and 1729 nm (PbS-D, Ø8 nm). Figure depicts the DPV results of all PbS QDs measured in TBAHFP/MeCN on a glassy carbon (GC) electrode (coloured curves) compared to the background of a blank GC electrode (grey curve). The measurements were initiated at the respective OCPs and in each scan direction, new PbS material was applied. The DPV results illustrate the often-complicated interpretation of electrochemical characterizations of QDs: surface defects, ligand instabilities and high film resistances can invoke inconclusive DPV signals, limited reversibility and sluggish charge carrier injection. From a previous report , one would expect a reductive wave at roughly -0.8 eV (the conduction band edge) and, consequently, an oxidative wave at 0.0 V. While the latter is reflected in the data, an unambiguous assignment is challenging, and a clear reductive wave at the anticipated potential is missing entirely. Similar inconclusive results are obtained by complementary cyclovoltammetric experiments (see Figure ). Overall, these difficulties already motivate the application of spectro-electrochemical techniques, such as EMAS, which can differentiate between band filling and electrochemical side reactions .