Graphene Bridge Heterostructure Devices for Negative Differential Transconductance Circuit Applications

Two-dimensional van der Waals(2D vdW)material-based heterostructure devices have been widely studied for high-end electronic applications owing to their heterojunction properties.In this study,we demonstrate graphene(Gr)-bridge heterostructure devices consisting of laterally series-connected ambipolar semiconductor/Gr-bridge/n-type molybdenum disulfide as a channel material for field-effect transistors(FET).Unlike conventional FET operation,our Gr-bridge devices exhibit nonclassical transfer characteristics(humped transfer curve),thus possessing a negative differential transconductance.These phenomena are interpreted as the operating behavior in two series-connected FETs,and they result from the gate-tunable contact capacity of the Gr-bridge layer.Multi-value logic inverters and frequency tripler circuits are successfully demonstrated using ambipolar semiconductors with narrow-and wide-bandgap materials as more advanced circuit applications based on non-classical transfer characteristics.Thus,we believe that our innovative and straightforward device structure engineering will be a promising technique for future multi-functional circuit applications of 2D nanoelectronics.

Organic photodiode with dual functions of indoor photovoltaic and high-speed photodetector

Energy harvesting and light detection are key technologies in various emerging optoelectronic applications.The high absorption capability and bandgap tunability of organic semiconductors make them promising candidates for such applications.Herein,a poly(3-hexylthiophene-2,5-diyl)(P3HT):indene-C60 bisadduct(ICBA)bulk heterojunction-based organic photodiode(OPD)was reported,demonstrating dual functionality as an indoor photovoltaic(PV)and as a high-speed photodetector.This OPD demonstrated decent indoor PV performance with a power conversion efficiency(PCE)of(11.6±0.5)%under a light emitting diode(LED)lamp with a luminance of 1000 lx.As a photodetector,this device exhibited a decent photoresponsivity of 0.15 A/W(green light)with an excellent linear dynamic range(LDR)of over 127 dB within the optical power range of 3.74×10^(−7) to 9.6×10^(−2) W/cm^(2).Furthermore,fast photoswitching behaviors could be observed with the rising/falling times of 14.5/10.4μs and a cutoff(3 dB)frequency of 37 kHz.These results might pave the way for further development of organic optoelectronic applications.