Developing bright and multicolor electrochemiluminescence (ECL) nano-emitters is widely pursued to achieve high sensitivity and multiplexing in bioassays and microscopy operating in physiological conditions. It is a particularly challenging task considering the specific requirements of charge injections and surface traps occurring in water during the ECL process. In this issue of ACS Central Science, Su, Peng, and coworkers rationalize the criteria of QDs architecture for ECL generation. 1 In an exciting report, they present elegantly designed water-soluble QDs with an impressive ECL efficiency. ECL is the light emitted by the excited state of a luminophore upon an electrochemical reaction (i.e. without photoexcitation). 2 The initial electron-transfer reaction at the electrode surface triggers a cascade of reactions involving energetic intermediates that leads in fine to the formation of the excited state. It relaxes to the ground state and emits a photon. It is a powerful analytical technique with an extremely low background because it combines the orthogonal modalities of electrochemical stimulation and optical detection. Thus, ECL crystallizes the beauty and complexity from both electrochemistry and photophysics. ECL is successfully commercialized for a large number of immunoassays, such as for cardiac and infectious diseases, thyroid, tumor markers, etc. Almost 2 billion ECL-based assays for clinical diagnostics run worldwide each year. 1 Since it is based on an optical readout, ECL has also evolved into a powerful imaging method. 3 Most of the applications still rely on the model [Ru(bpy) 3 ] 2+ or cyclometalated Ir(III) luminophores with a sacrificial coreactant species. 4 Many works have been carried out to improve the ECL efficiency in water. 5 Indeed, brighter ECL emitters and various emission colors are highly desirable due to the increasing demand for accuracy and multiplexing in microscopy and diagnostics. Colloidal quantum dots (QDs), which are semiconductor nanocrystals (NCs) exhibit unique quantum size effects. Their electronic, optical, and electrochemical properties depend strongly on their size, shape and surface chemistry due to their very high surface area-to-volume ratio that may lead to various heterogeneous redox reactions with the surrounding environment. In a seminal work h y 2000' , Ding et al. reported the ECL from silicon QDs. 6 After that, a large variety of semiconductor materials such as Ge, CdTe, CdSe, and PbSe have been explored to generate ECL. But, in most cases, surface reactivity can lead to the formation of electronic traps for electrons and holes, which strongly inhibit the ECL process by translating into poor efficiency. Indeed, depending on the semiconductor and its intrinsic f h m y h QD ' h m v y result in either disastrous characteristics or original useful performances. 7 As nicely discussed in the article, 1 ECL of QDs corresponds to a very different situation in comparison to photoluminescence (PL) and electroluminescence. In the ECL process (Figure