Improved performance of organic photovoltaic devices by doping F4TCNQ onto solution-processed graphene as a hole transport layer

Interfacial engineering is crucial for the stability and efficiency of organic solar cells. PEDOT:PSS, which has been widely used as a hole transport layer, has stability issues when exposed to air because of its acidic and hygroscopic nature. Herein, we investigated the electrical properties of reduced graphene oxide covered with an F₄TCNQ interfacial layer as an alternative and its effect on the photovoltaic performance. Using an array of charge transport, spectroscopic and imaging techniques we found that the reduced graphene oxide film is efficiently hole-doped through an interfacial charge transfer, which enhances its electrical properties and favorably modifies its work function. Consequently, the open-circuit voltage and fill factor of solar cells incorporating such films are improved. P3HT might also be hole-doped by F₄TCNQ, due to the formation of an intermixed interfacial layer, resulting in an increase of power conversion efficiency.     

N-type polymeric organic flash memory device: Effect of reduced graphene oxide floating gate

In this paper, n type nonvolatile memory devices were fabricated by implanting a bilayer (rGO sheets/Au NP) floating gates, using n-type polymer semiconductor, poly {[N, N′ bis (2octyldodecyl) - naphthalene-1, 4, 5, 8 - bis (dicarboximide)-2,6-diyl] – alt - 5,5′ - (2, 2′ bithiophene)} [P(NDI2OD-T2)n]. In the developed organic field effect transistor memory devices, electrons are trapped/detrapped in rGO sheet/Au NP's nano-floating gates by controlling the charge carrier density in the active layer through back gate bias control. The devices showed interesting non-volatile memory properties with a large memory window of ∼34 V, a programming-reading-erasing cycling endurance of 103 times and most importantly, an improved retention time characteristics estimated by extrapolation (longer than the technological requirement of commercial memory devices (>10 years)). This approach provides a great potential for fabricating high-performances organic nano-floating gate memory devices and opens up a new way for the development of next-generation non-volatile memory devices.