Comparative Study on the Photovoltaic Properties of ZnX (X = S, Se, Te) QD/CNT Inorganic/Organic Hybrid Nanocomposites

Abstract

Designing the efficient inorganic/organic hybrid light harvesting systems through understanding of charge generation, separation, and recombination dynamics is an important pathway for improvement of power conversion efficiency (PCE) of the photovoltaic cell. Using the density functional method, we explored the photovoltaic performance of recently synthesized ZnX (X = S, Se, Te) QD/carbon nanotube (CNT) nanocomposites. Interestingly, ZnX QD/CNT nanocomposites exhibit type-II band alignment, where hole and electron charge carriers are localized on ZnX QD and CNT, respectively. However, the energy difference between the highest occupied molecular orbital of ZnX QD and the conduction band minimum of CNT is very small (0.09−0.26 eV), implying huge possibilities of electron−hole recombination at the ZnX:CNT interface. To overcome such an unpleasant situation, we focus on chemical modification of CNT. The CNT is hydrogenated by attachment of atomic hydrogen and, next, the hydrogenated CNT is functionalized by the electron withdrawing group (−CN) in part. We found that ZnX QD and CN-functionalized hydrogenated CNT nanocomposites exhibit intended type-II band alignment and achieve high PCEs in the range of 6.73−8.38%, making them exceptionally competitive with other previously reported hybrid solar cells.

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

“…Now the question is whether it is possible to achieve spatial charge separation of CdXQD/P3HT composites also for smaller-size CdXQDs. Our previous studies have shown that the chemical functionalization can tune the electronic energy levels effectively and finally make them suitable for solar energy conversion devices. − Experimentally and theoretically, the hydrogen (H) and halogen atoms (F, Cl) and the pseudohalogen group (CN) , are extensively used for chemical functionalization. The chemical modification to the polymer P3HT may be an important step toward the realization of the type-II hybrid system based on CdXQD/P3HT composites.…”

CNTs modified ZnO and TiO2 thin films: The effect of loading rate on band offset at metal / semiconductor interfaces

“…They are already used in the fields of sports equipment, aeronautics, automobiles, defence, medicine, etc. Nanotube powder also has multiple potential applications such as hydrogen storage, the manufacture of batteries for electric cars and photovoltaic [28] The CNTs used in the experiments were prepared by chemical vapor deposition, and purified through the treatment of the concentrated mixed acid (nitric acid and hydrochloric acid), which was described in detail elsewhere [29][30].…”

Tunable Electronic Structure of Two-Dimensional MoX2 (X = S, Se)/SnS2 van der Waals Heterostructures

“…The type-I band alignment is widely used in optoelectronic devices such as light-emitting diodes (LEDs) and lasers . Type-II band alignment, where VBM and CBM are localized on two independent 2D materials, respectively, facilitates the spatial separation of photogenerated electron and hole charge carriers, making them potentially useful for applications in electronic devices like field-effect transistors , and photovoltaics. − …”