Quantum Dot Sensitized Solar Cell Based On Mesoporous TiO₂ Photoanode

Quantum dot- sensitizedsolar cell（QDSC） constitutes one of the most promising candaite for the third-generation solar cells due to band gap tunability, high absorption coefficient, solution processibility as well as multiexciton generation（MEG） which could boost theoretical power conversion efficiency（PCE） beyond the Shockley-Queiseer limit of 31%. In this paper, our work mainly focuses on the effect of QD-sensitzed mesoporous TiO₂ photoanode on the resulting performance of QDSC employing polysulfide and Cu2 S counter electrode.In this paper,three cationic precursors, Cd（NO3）2, CdCl2, and Cd（AC）2, were selected for preparation of CdS QDSC by successive ionic layer absorption and reaction（SILAR）. The CdS QD sensitized photoanode based on effective cationic precursor, Cd（Ac）2, exhibits broader light-harvesting range, higher photocurrent response value, higher QD loading, efficient elelctron-injection efficiency, thus the resulting solar cell achieved the power conversion efficiency（PCE） of 2.10%. The cationic precursor effect was further applied to PbS/CdS QD co-sensitized solar cell. The PbS/CdS QDSC employing acetate slats as precursors achieved the photocurrent of 19.24 mA/cm2, and PCE of 3.23%. In SILAR, the cationic precursor effect opens up a way to effectively improve the performance of QDSC.In this work, we have fabricated PbS/C5H5N/CdS/ZnS QD-sensitized solar cell sbubjected to inorganic and organic passivation, and its light-harvesting range covers the whole visible spectrum and extends to near-infrared region. Compared to PbS/CdS/ZnS QD-sensitized solar cell, PbS/C5H5N/CdS/ZnS QD-sensitized solar cell had higher QD loading and higher electron-injection efficiency, we achieved the photocurrent of 21.25 mA/cm2 and the PCE of 3.65%. PbS/C5H5N/CdS/ZnS QD-sensitized solar cell exhibited good photocurrent stability.We have prepared CdS/CdSe QD co-sensitized solar cell by combing SILAR and chemical bath deposition（CBD） method and study the effect of pH values on the effect of QDSC perfeomance. At pH=10,CdS/CdSe QD-sensited solar cell achieved photocurrent response at ～700 nm by combination of uniform distribuction of QDs throughout the porous TiO₂ electrode and higher electron-injection efficiency. CdS/CdSe QD-Sensitized solar cell obtained the PCE of 3.93% and posessed good photovoltaic parameters: Jsc=11.46 mA/cm2, Voc=0.577 V, FF=0.595.Based on the work methioned above, we conclude that light-harvesting rang, electron-injection efficieny, QD sensitzer loading on TiO₂ film play important roles in the performace of QDSC.