Title
High‐Yield Generation of Triplet Excited States by Efficient Sequential Photoinduced Process from Energy Transfer to Singlet Fission in Pentacene‐Modified CdSe/ZnS Quantum Dots
Author
Hayato Sakai, Ryutaro Inaya, Nikolai V. Tkachenko, Taku Hasobe
Year
2018
Journal
Chemistry A European Journal
Abstract
Singlet fission (SF) is expected to improve the photo energy conversion systems by generating two electrons from one photon. Pentacenes meet the energy level matching condition between singlet and two triplet states: [E(S1) ≥ 2E(T1)]. However, the molar absorption coefficients of pentacenes in ca. 400-500 nm region are limited, whereas quantum dots such as CdSe/ZnS (QD) possess high fluorescence quantum yields and particle sizedependent fluorescence wavelengths. Thus, a combination of QD (D) and pentacene (A) provides a system of both an enhanced light harvesting efficiency throughout the solar spectrum and an efficient conversion of the harvested light into the triplet states by SF. Based on these points, m-phenylene-bridged TIPS-pentacene dimerfunctionalized QD [denoted as m-(Pc)2-QD] was synthesized to examine the sequential photoinduced process from energy transfer to SF. In femtosecond transient absorption measurements, initial energy transfer from QD to pentacene (quantum yield: 87%) and subsequent SF were efficiently observed. The quantum yield of triplet states of pentacene units (ΦΤ) based on the excitation of QD attained 160 ± 6.7%.
Instrument
FP-8500
Keywords
Fluorescence, Quenching, Chemical stability, Optical properties, Materials