Abstract
This paper reviews our recent work on the pulsed laser processing of graphene and related two-dimensional (2D) materials. In particular we report on a rapid and facile method for the simultaneous reduction, doping[1] and functionalization[2] of GO. This technique is compatible with flexible, temperature sensitive substrates and was initially applied for the efficient production of highly transparent and conductive flexible graphene-based electrodes. It is based on the use of femtosecond laser irradiation for the in-situ, non-thermal, reduction of spin coated GO films on flexible substrates over a large area. Furthermore, we present a fast, non-destructive and roll to roll compatible photochemical method for the simultaneous partial reduction and doping of GO nanosheets through ultraviolet laser irradiation in the presence of reactive Cl2 precursor molecules [1]. By tuning the laser exposure time, it is possible to control the doping and reduction levels and therefore to tailor the work function (WF) of the GO-Cl derivatives from 4.9 eV to a maximum value of 5.23 eV, a WF value that matches the HOMO level of most polymer donors employed in OPV devices [3]. Moreover, we demonstrate the pulse UV laser - assisted photochemical functionalization of GO with small molecules as an efficient technique to realize polymer electron acceptors [2]. Finally, we report on the morphological effects induced upon the interaction of ultrashort laser pulses with transition metal dichalcogenide 2D crystals [4]. Experiments show that for fluences slightly above the damage threshold, a rippled morphology is attained. Besides this, decoration of nanosheets with NPs can be realised through excimer laser irradiation of colloidal dispersions of 2D flakes in the presence of NPs dispersed in solution. Potential applications of pulsed laser synthesized and modified materials in electronics, particular to bulk heterojunction organic solar cells are demonstrated and discussed.
© 2015 IEEE
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