Improved optical and electrical response in metal–polymer nanocomposites for photovoltaic applications

Hybrid nanocomposites based on polyethylene glycol (PEG) embedded with nanoscopic Ag particles were prepared by two distinct approaches: in situ and ex situ chemical processing routes. The effect of Ag loading on tailored optical and electrical responses in the two classes of metal–polymer nanocomposites (MPNs) was investigated. Transmission electron microscopy of the in situ MPN sample revealed core–shell-type combination comprising Ag nanoparticles lying at the core surrounded by polymeric (PEG) shell. On the other hand, ex situ MPNs exhibited dispersed phase microstructure with uneven distribution of Ag nanoparticles in the PEG matrix. Comparison of the thermal properties of in situ and ex situ MPNs confirmed that the MPN obtained through in situ process with 2 wt% of Ag contents displayed higher thermal stability (≈18%) relative to ex situ MPN of the same composition. The absorption spectrum confirmed clear, blue shift with enhanced band gap in the case of in situ MPN relative to its ex situ counterpart. The Ag–PEG nanocomposites prepared by both the processes exhibited metallic I–V response. Electrical transport observed in terms of resistivity variation with temperature confirmed typical semiconducting behavior in the composite phase in sharp contrast to the insulating property of the host PEG. A large decrease (≈65%) in activation energy was observed in the case of in situ MPN at higher loading of Ag possibly because of the higher mobility assisted by tunneling of charge carriers through polymeric spacers in the composite phase. The drastic improvement in optical and electrical responses of the nanocomposites indicated the suitability for photovoltaic and optoelectronic applications.