Efficient quantum dot sensitized solar cells via improved loading amount management

High light-harvesting efficiency and low interfacial charge transfer loss are essential for the fabrication of high-efficiency quantum dot-based solar cells(QDSCs). Increasing the thickness of mesoporous TiO2films can improve the loading of pre-synthesized QDs on the film and enhance the absorbance of photoanode, but commonly accompanied by the increase in the unfavorable charge recombination due to prolonged electron transmission paths. Herein, we systematically studied the influence of the balance between QD loading and TiO2film thickness on the performance of QDSCs. It is found that the relative thin photoanode prepared by the cationic surfactant-assisted multiple deposition procedure has achieved a high QD loading which is comparable to that of the thick photoanode commonly used. Under AM 1.5G illumination, Zn–Cu–In–Se and Zn–Cu–In–S based QDSCs with optimized 11.8 μm photoanodes show the PCE of 10.03% and 8.53%, respectively, which are comparable to the corresponding highest PCE of Zn–Cu–In–Se and Zn–Cu–In–S QDSCs(9.74% and 8.75%) with over 25.0 μm photoanodes. Similarly, an impressive PCE of 6.14% was obtained for the CdSe based QDSCs with a 4.1 μm photoanode, which is slightly lower than the best PCE(7.05%)of reference CdSe QDSCs with 18.1 μm photoanode.

Large-scale heterogeneous synthesis of monodisperse high performance colloidal CsPbBr_(3)nanocrystals

Colloidal lead halide perovskite nanocrystals(LHP NCs)are promising semiconductor materials for optoelectronic devices,but the high ionicity of LHP NCs makes their crystallization control and post-treatment difficult.Here,phosphonic acids(PAs)are employed as ligands to design a solid-liquid heterogeneous reaction system to regulate the LHP NC crystallization and achieve the desired focusing growth.During the heterogeneous synthesis,the precursors in the liquid phase are responsible for the burst nucleation and initial growth of NCs.Afterwards,the focusing growth of NCs is supported by the precursors released from the solid phase.In addition,the strong binding ability of PAs enables effective passivation of LHP NCs.Without post-treatment,gram-scale monodisperse CsPbBr_(3)NCs having photoluminescence with a full width at half-maximum of 18 nm and a quantum yield of near-unity are obtained.The CsPbBr_(3)NCs covered by a compact ligand layer keep initial quantum yield even after 18 cycles of purification,exhibiting excellent stability against polar solvents,ultraviolet irradiation and heat treatment.As scintillators,the prepared CsPbBr_(3)NCs show strong radioluminescence emission and high-resolution X-ray imaging.

Highly luminescent and stable CsPbBr3 perovskite quantum dots modified by phosphine ligands

All-inorganic cesium lead halide perovskite quantum dots (QDs) have been a promising candidate for optoelectronic devices in recent years,such as light-emitting diodes,photodetectors and solar cells,owing to their superb optoelectronic properties.Still,the stability issue of nanocrystals is a bottleneck for their practical application.Herein,we report a facile method for the synthesis of a series of phosphine ligand modified CsPbBr3 QDs with high PL intensity.By introducing organic phosphine ligands,the tolerance of CsPbBr3 QDs to ethanol,water and UV light was dramatically improved.Moreover,the phosphine ligand modified QD films deposited on the glass subtracts exhibit superior PL intensity and optical stability to those of pristine QD based films.

Aluminum Distearate-Modified CsPbX_(3)(X=I,Br,or Cl/Br) Nanocrystals with Enhanced Optical and Structural Stabilities

Colloidal all-inorganic perovskite nanocrystals(PNCs),possessing unique optical properties,have attracted considerable attention in the field of semiconductor nanocrystals(NCs),but their application is hindered by the stability issue resulting partly from dynamic capping ligand binding.Herein,we report a simple method for the synthesis of all-inorganic cesium lead-based(CsPbX3)NCs with enhanced structural stability and photoluminescence quantum yield.Aluminum distearate(AlDS)was introduced into the preparation of CsPbX3 NCs,on the basis that the surface defects of CsPbX3 NCs are passivated to form a protective layer on the CsPbX3 NC surface simultaneously.Benefiting from surface modification,the resistance of the CsPbX3 NC dispersion against ethanol,ultraviolet irradiation,and heat treatment was enhanced effectively.Moreover,the photoluminescence intensity and stability of the AlDS–modified NC-based films displayed functional superiority to those of pristine NC-based films.