Composite interfacial modification in TiO2 nanorod array/poly(3-hexylthiophene) hybrid photovoltaic devices

Highlights: •Organic modifiers can improve the efficiencies of hybrid devices. •Composite interfacial modification had superior performances than monolayer. •The efficiencies of TiO2/CdSe/N719/P3HT had a significantly improvement over 8 times. -- Abstract: Interfacial modification is an important approach to improve the efficiencies of organic/inorganic hybrid solar cells. A novel strategy of composite interfacial modification in TiO2 nanorod array/poly(3-hexylthiophene) (P3HT) hybrid solar cells had been proposed and carried out. The interfacial modification mechanism had been investigated comprehensively by considering various aspects such as light harvesting, carrier separation, charge recombination and energy level alignment. The results show that monolayer modifiers such as N719 or pyridine (PYR) can improve chemical incompatibility, accelerate carrier separation and reduce charge recombination. Composite interfacial modification had been realized by introducing CdSe, in which enhanced light harvesting was observed as well as the pre-existing advantages. The efficiencies of composite interfacial modified hybrid solar cells based on TiO2/CdSe/PYR/P3HT and TiO2/CdSe/N719/P3HT reached to 0.28% and 0.51%, which were 33% and 45% higher than that based on TiO2/PYR/P3HTand TiO2/N719/P3HT, respectively