Carbon Nanosheet from Polyethylene Thin Film as a Transparent Conducting Film: “Upcycling” of Waste to Organic Photovoltaics Application

In this work, we demonstrate the successful transformation of a polyethylene (PE) thin film into an effective transparent conducting film (TCF). Through thermal oxidative stabilization, an innately noncarbonizable PE thin film could survive carbonization process and converted into a carbon nanosheet (CNS). Interestingly, unlike other CNSs fabricated from pricey sources, those from PE, one of the cheapest polymers, included highly ordered graphitic moieties confirmed by combination of Raman spectra analyses and transmission electron microscopy (TEM). Inclusion of graphitic moieties endowed superior electrical conductivity to PE based CNSs over other CNSs and TCFs without harshly compromising other figures of merits as TCFs. Effectiveness of CNSs as TCFs was assessed by fabricating organic photovoltaic cells (OPVs). OPVs structured on PE CNSs successfully operated and exhibited sound efficiencies. More significantly, PE wastes could be equivalently transformed into CNSs and OPVs as pristine PE did, suggesting possible pathway providing extra financial value to PE wastes; it is worthy to note that PE waste is the largest polymer waste in volume and is mostly buried or burnt. Thus, the technology introduced in this article has profound potential as an effective solution to deal with environmental problems associated with PE wastes by envisioning viable “upcycling” pathway of the wastes.