Given the toxicity of lead, there is ongoing research into the discovery of lead-free perovskites for optoelectronics. Several lead-free perovskites have been prepared colloidally: Cs3Bi2I9, Cs2PdX6, CsSnX3. CsSnX3 NCs, although the closest lead-free analogue to the highly luminescent CsPbX3 NCs, do not exhibit high quantum yields (<1% PLQY) CsSnX3 NCs are also sensitive towards O2 which causes oxidation of Sn(II) to Sn(IV) and renders the NCs non-luminescent.
