High current density cation-exchanged SnO 2 –CdSe/ZnSe and SnO 2 –CdSe/SnSe quantum-dot photoelectrochemical cells

• Published in: New journal of chemistry 2018, Vol.42 (11), p.9028-9036
• Main Authors: Naushad, Mu, Khan, M. R., Bhande, Sambhaji S., Shaikh, Shoyebmohamad F., Alfadul, S. M., Shinde, Pritamkumar V., Mane, Rajaram S.
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C8NJ01409D

Research on the combination of low and high-bandgap energy materials through an ion-mediated chemical transformation of the nanostructure of one material into another, especially metal chalcogenide quantum dot (QD) solar cells plays a very important role in the fast charge transformation process with high power conversion efficiencies (PCE) by reducing surface charge recombinations. Based on a coordination chemistry approach, the present study demonstrates the importance of cation-exchange process in developing bandgap engineering of tin oxide–cadmium selenide (SnO 2 –CdSe) with zinc selenide (ZnSe) and tin selenide (SnSe) to form SnO 2 –CdSe/ZnSe and SnO 2 –CdSe/SnSe electrodes, respectively. Experimental conditions are optimized from optical and photovoltaic performances. Our best performing cation-exchange interface-modified photoelectrochemical devices, i.e. , SnO 2 –CdSe/ZnSe and SnO 2 –CdSe/SnSe have achieved improvements of 21% and 28%, respectively, in their PEC values, i.e. , 3.78% and 4.41% with remarkable current densities of 19.82 and 28.40 mA cm −2 when compared with SnO 2 –CdSe (1.63% and 9.74 mA cm −2 ). This is due to (a) the fast transfer of photo-generated electrons from the CdSe QD sensitizer to SnO 2 photoanode by engineering a synergistically favourable band gap and (b) mitigation of a reverse photogenerated electron flow in the presence of a high band gap buffer ZnSe/SnSe layer, which would otherwise cause excessive recombinations. A simple cation-exchange interface modification process can, in general, pave the way for improving the performance of QD-based solar cells.