Molecular engineering for high-performance fullerene broadband photodetectors

Abstract

Broadband photodetectors fabricated with organic molecules have the advantages of low cost, high flexibility, easy processing and low-temperature requirement. Fullerene molecules, due to their electron accepting and photoinduced electron transfer properties, are potential materials for photodetectors. However, fullerene has a narrow light absorption spectrum range, and realization of large-area fullerene-based broadband photodetectors remains a challenge. Herein, we broaden the absorption wavelength range of fullerene through molecular engineering, i.e. adding a donor molecule, nickel tetraphenylporphyrin (NiTPP) with strong visible light absorption capacity, onto the fullerene cage to form a donor–acceptor dyad (NiTPP-C₆₀). Moreover, large-area nickel porphyrin–fullerene (NiTPP-C₆₀) single-crystal arrays were prepared by applying a liquid-bridge induced assembly method. Combining the excellent visible light absorption properties of porphyrin and the good electron transport characteristic of fullerene, photodetectors fabricated with NiTPP-C₆₀ single-crystal arrays show a fast photoelectric response with τ_on < 0.09 s at 350 nm, τ_on < 0.10 s at 425 nm and τ_on < 0.08 s at 530 nm, and the highest responsivity of 11.9 A W⁻¹ at 425 nm. This study provides a new strategy toward the fabrication of high-performance fullerene broadband photodetectors and presents a versatile method for the design of large-area well-aligned organic single-crystal arrays for practical electronic applications.