Enhanced Photovoltaic Performance of CdS Quantum Dot-Sensitized Solar Cells Using 4-Tertbutylbenzoic Acid as Self-Assembled Monolayer on ZnO Photoanode

A 4-tertbutylbenzoic acid (BBA) self-assembled monolayers (SAMs) layer derived from benzoic acid is fabricated on the surface of photoanodes with different spin-coating cycles. The effects of BBA on the photovoltaic property of the device are investigated. The conversion efficiency of the photovoltaic property with BBA/ZnO photoanodes exhibits a 56% enhancement in comparison with solar cells with pure ZnO photoanodes. The enhancement of the conversion efficiency is attributed to two aspects. The first one is that BBA SAMs in CdS quantum dots-sensitized solar cells can suppress recombination process of electron-hole because BBA decreased the defects on ZnO surface. The second one is that energy barrier formed by BBA efficiently prevent electrons transfer to CdS quantum dots. Ultimately, the photovoltaic performance of solar cells increased after deposition of BBA SAMs layer. Our experimental method provides an effective method for increasing the conversion efficiency of new generation solar cell device.