Top Laminated Graphene Electrode in a Semitransparent Polymer Solar Cell by Simultaneous Thermal Annealing/Releasing Method

Abstract

In this article, we demonstrate a semitransparent inverted-type polymer solar cell using a top laminated graphene electrode without damaging the underlying organic photoactive layer. The lamination process involves the simultaneous thermal releasing deposition of the graphene top electrode during thermal annealing of the photoactive layer. The resulting semitransparent polymer solar cell exhibits a promising power conversion efficiency of approximately 76% of that of the standard opaque device using an Ag metal electrode. The asymmetric photovoltaic performances of the semitransparent solar cell while illuminated from two respective sides were further analyzed using optical simulation and photocarrier recombination measurement. The devices consisting of the top laminated transparent graphene electrode enable the feasible roll-to-roll manufacturing of low-cost semitransparent polymer solar cells and can be utilized in new applications such as power-generated windows or multijunction or bifacial photovoltaic devices.

Fully Solution-Processed Semitransparent Organic Solar Cells with a Silver Nanowire Cathode and a Conducting Polymer Anode

“…Despite their fully solution-processed nature, they are comparable in efficiency to previously reported semitransparent OSCs with ITO, which have been reported to have PCEs in the range 1.9 to 2.5 %. [27][28][29][30][31] The efficiencies also compare well with a very recent report by Guo et al 32 where PCEs of 2.3 % were achieved using AgNWs for both electrodes (although, in contrast to the devices described here, a ternary-blend of P3HT, …”

Semi-transparent polymer solar cells

“…This electrode must be deposited when the absorber layer has already been deposited on the substrate and a nonaggressive deposition procedure needs to be used. Several different options have been considered, such as low-temperature annealed indium tin oxide (ITO), [42][43][44][45][46][47][48] a three-layer architecture combining a dielectric layer, an ultra thin metal layer, and a second dielectric layer, [49][50][51][52][53][54][55][56][57][58][59][60][61][62][63][64] PEDOT, [65][66][67] silver grid, 68 graphene, [69][70][71] carbon nanotubes, 67,72 and silver nanowires (AgNW). [73][74][75][76][77][78] However, the need for a nondestructive deposition technique for the top semi-transparent electrode is probably not the major issue that semi-transparent OPV cells must overcome before becoming an industrially viable solution.…”

All-Carbon Electrodes for Flexible Solar Cells

“…As for the G-G cell, its performance is close to that of its G-ITO counterpart, showing the great potential of graphene to substitute the traditional metal grid. Moreover, the current densities of devices with all-carbon electrodes are comparable to those of devices based on an organic active layer with electrodes made of carbon-based and standard materials [29,31,33,45,48,56]. These results suggest that all-carbon electrodes composed of CNT and graphene films could efficiently collect and transport charge carriers towards an external circuit.…”

“…Thus, the CVD process is preferable for the preparation of thin films with a large area, intact structure, and low number of defects for either CNT or graphene. Concerning cathodes, CNT and graphene films were used to substitute the conventional metal grid combined with ITO; consequently, it became possible to fabricate semi-transparent OPVs that could be illuminated at both sides [26,31,48]. However, carbon-based flexible electrodes are applied only on one side of abovementioned OPVs, which still involve brittle ITO or noble metals.…”