Direct covalent modification of black phosphorus quantum dots with conjugated polymers for information storageElectronic supplementary information (ESI) available. See DOI: 10.1039/c8nr09711a

It has long been recognized that a small switching bias window, which is defined as the difference between the switch-on and switch-off voltages (Δ| V ON − V OFF |), and a high ON/OFF current ratio would be greatly favorable to reduce the power consumption of memory devices and to decrease the information misreading rate in digital memory devices. In contrast to two-dimensional BP nanosheets, zero dimensional BP quantum dots (BPQDs) show more exciting physical and chemical properties. By using newly synthesized poly[(9,9-dioctyl-9 H -fluorene)- alt -(4-(9 H -carbazol-9-yl)aniline)] (PFCz-NH 2 ) as the synthetic precursor, a highly soluble diazotated polymer, PFCz-N 2 + BF 4 − , was successfully synthesized and used to react with BPQDs under aqueous conditions to give the first conjugated polymer covalently functionalized BPQDs (PFCz- g -BPQDs). The as-prepared Al/PFCz- g -BPQDs/ITO device exhibits excellent nonvolatile rewritable memory performance, with a large ON/OFF current ratio (>10 7 ) and low switch-on/off voltages (−0.89/+1.95 V). In contrast, the Al/PFCz-NH 2 : BPQDs blend/ITO device also shows a rewritable memory effect, but its ON/OFF current ratio and Δ| V ON − V OFF | value are found to be 3 × 10 3 and 5.47 (Δ|+2.53-2.94|), respectively. This work, which offers an easy one-step strategy for direct covalent functionalization of BPQDs, opens a way to explore more applications of BPQDs. By using a one-step synthetic strategy, the first conjugated polymer covalently functionalized BPQDs have been synthesized. This material exhibits an excellent nonvolatile rewritable memory effect, with a large ON/OFF current ratio (>10 7 ) and a low switch-on voltage (−0.89 V).