Improving Humidity Sensing of Black Phosphorus Nanosheets by Co-Doping Benzyl Viologen and Au Nanoparticles

Black phosphorus (BP) is a two-dimensional and layered elemental semiconductor that is very sensitive to the subtle fluctuation of relative humidity (RH). However, the practical application of BP material was undesirably plagued by the irreversible degradation under moisture/oxygen atmospheres. To circumvent this limitation, here we prepared BP co-doped with benzyl viologen (BV) and Au nanoparticles as the sensing layer and explored the humidity-sensing performance at room temperature (20 oC). Unlike BP (BP-BV) counterparts, BP-Au (BP-BV-Au) sensors demonstrated unvaried response polarity with increasing RH. And BV introduction improved the recovery characteristics. Additionally, the ternary BP-BV-Au sensors delivered decent selectivity and negligible hysteresis. On the one hand, the in situ reduction of Au nanoparticles consumed lone electron pairs within BP, suppressed the interaction with ambient moisture/oxygen, and improved the operation stability and recovery. On the other hand, hydrophobic BV as the protection layer further hindered water attachment. This co-doping behavior reduced the hole density and ensured the predominant interaction between low-energy sorption sites within BP and water molecules, thus leading to a larger resistance modulation (i.e., stronger response) and quicker reaction kinetics. This work offered a feasible method to propel the practical application and enriched the sensing mechanisms of BP-based humidity sensors.

Electron n-doping of a highly electron-deficient chlorinated benzodifurandione-based oligophenylene vinylene polymer using benzyl viologen radical cations

Successful electron-doping of highly electron-deficient chlorinated benzodifurandione-based polyphenylene vinylene using viologen radical cation.

High-performance & thermally stable n-type polymer thermoelectrics based on a benzyl viologen radical cation-doped ladder-type conjugated polymer

Viologen radical cation doped poly(benzimidazobenzophenanthrolinedione) (BBL) has shown enormous potential for high performance and thermally stable n-type polymer thermoelectrics.

Benzyl viologen radical cation: an effective n-dopant for poly(perylenediimide-bithiophene)

Poly(perylenediimide-bithiophene) can be efficiently n-doped by benzyl viologen radical cation and its thermoelectric performance was measured for the first time.