Highly Efficient Inorganic-Organic Heterojunction Solar Cells Based on Polymer and CdX (X=Se, Te) Quantum Dots: An Insight from a Theoretical Study

摘要： By using the density functional method, we explore the potentiality of recently synthesized CdX (X=Se, Te)QD/P3HT composites in solar energy conversion devices. Our study reveals that inorganic/organic hybrid CdXQD/P3HT nanocomposites with larger size of CdX QDs exhibit type-II band alignment, suggesting efficient charge separation upon photoexcitation. But for smaller size of QDs, the composites show type-I band alignment which are devoid of charge separation and thus are not suitable for solar cell applications. To remove this obstacle, we focus on chemical modification to polymer P3HT. The substitution of hydrogen at the beta position of each thiophene ring of polymer by electron withdrawing group (CN) results type-II band alignment and yield spatial charge separation even for smaller size of QDs. Finally, we calculated the powerconversion efficiency (PCE) of CdXQD and CN functionalized P3HT nanocomposites. The maximum calculated PCE value of 10.82% is achieved, which makes them immensely competitive with other reported heterojunction solar cells.