Black Phosphorus Quantum Dots as Hole Capturers in Group-VA Monoelemental Heterostructures for the Application of High-Performance Flexible Photodetectors

Herein, black phosphorus (BP) quantum dots (QDs) with consistent sizes are loaded on bismuth (Bi) nanosheets (NSs) uniformly to serve as hole capturers in Group-VA monoelemental heterostructures via a facile sonication approach. The as-fabricated Bi NSs-BP QD-based photodetectors exhibit 4.6 μA/cm2 photocurrent density at applied 0.8 V bias potential, about 4.2 times enhancement compared to Bi NSs, which contributes to the construction of type-II heterojunctions that effectively restrain the recombination of electron–hole pair and accelerates the transfer rate of carriers. Additionally, the photocurrent density of Bi NSs-BP QD-based photodetectors reaches 100 nA/cm2 without external power supply, allowing fabricated devices to work normally in an emergency. Meanwhile, long-cycle stability measurements reveal 15% photocurrent density attenuation after 2000 bending times and 8.8% under 60° bending angles. This work proves that the introduction of BP QDs significantly improves the performance of the Bi-based photodetector and provides a novel strategy to construct flexible photodetectors.