Surface Chemistry Engineering of Perovskite Quantum Dots: Strategies, Applications, and Perspectives

Abstract

The presence of surface ligands not only plays a key role in keeping the colloidal integrity and non‐defective surface of metal halide perovskite quantum dots (PQDs), but also serves as a knob to tune their optoelectronic properties for a variety of exciting applications including solar cells and light‐emitting diodes. However, these indispensable surface ligands may also deteriorate the stability and key properties of PQDs due to their highly dynamic binding and insulating nature. To address these issues, a number of innovative surface chemistry engineering approaches have been developed in the past few years. Based on an in‐depth fundamental understanding of the surface atomistic structure and surface defect formation mechanism in the tiny nanoparticles, a critical overview focusing on the surface chemistry engineering of PQDs including advanced colloidal synthesis, in‐situ surface passivation, and solution‐phase/solid‐state ligand exchange is presented, after which their unprecedented achievements in photovoltaics and other optoelectronics are presented. The practical hurdles and future directions are critically discussed to inspire more rational design of PQD surface chemistry toward practical applications.

Autonomous Nanocrystal Doping by Self‐Driving Fluidic Micro‐Processors

“…Additionally, as shown in Figure 6A, increasing the OA concentration results in an increase of E P values as extra oleate ions in the reaction environment avoid chloride exchange reactions to happen due to the removal of the OAm–Cl ligand shell from the surface of the NCs. [ 57,58 ] Similarly, SHAP analysis of R A values shown in Figure 6B reveals that concentrations of SnCl 4 , OA–TOL, and Mn(Ac) 2 are the most important input parameters affecting the extent of R A . Further information regarding the effect of each of the identified key parameters on R A values is provided in Supporting Information S6.…”

“…CsPbBr 3 NCs have a ligand shell consisted of x-type OAm-Br and OAm-OA complexes bound to the surface of NCs besides oleate ions attached to Cs or Pb by occupying the halide sites. [57,60] Purification of the CsPbBr 3 NCs with methyl acetate can remove major portion of oleate ions from the ligand shell, [58] resulting in formation of numerous Pb 2þ and Cs þ vacancies on the surface of NCs. Also, further dilution of the washed NCs can result in breakage of the OAm-Br bindings, and thus the formation of additional surface defects.…”

Colloidal Quantum Dot Solar Cells: Progressive Deposition Techniques and Future Prospects on Large‐Area Fabrication

“…[29b,91,93] A variety of alternative surface treatments have been developed in order to improve the inter-dot electronic coupling, carrier transport, and overall PV performance. [94] To more efficiently remove the oleate ligands, Jigeon et al further introduced a modification that involves treating the CsPbI 3 PQD films with a solution of sodium acetate (NaOAc) in MeOAc. [92] Unlike the neat MeOAc treatment, this NaOAc treatment contains OAc ions without the formation of the hydrolysis byproducts: methanol and proton.…”

Perovskite Quantum Dots in Solar Cells

“…Therefore, the synthesis is followed by multi‐post‐treatment process essentially to modulate the capping ligands, i.e., ligand engineering, while ensuring the integrity of PQDs in parallel with precluding aggregation. [ 36 ] In the following part, we will systematically review the ligand engineering for PQDs including post‐purification process to control the ligand density and ligand‐exchanging processes to regulate ligand species, according to the preparative route of PQD films.…”