Graphene with Ni-Grid as Semitransparent Electrode for Bulk Heterojunction Solar Cells (BHJ-SCs)

Abstract

In this work, we present the fabrication and characterization of bulk-heterojunction solar cells on monolayer graphene (MLG) with nickel-grids (Ni-grid) as semitransparent conductive electrode. The electrodes showed a maximum transmittance of 90% (calculated in 300–800 nm range) and a sheet resistance down to 35 Ω/□. On these new anodes, we fabricated TCO free BHJ-SCs using PTB7 blended with PC70BM fullerene derivative as active layer. The best device exhibited a power conversion efficiency (PCE) of 4.2% in direct configuration and 3.6% in inverted configuration. The reference solar cell, realized on the ITO glass substrate, achieved a PCE of 6.1% and 6.7% in direct and inverted configuration respectively; for comparison we also tested OSCs only with simple Ni-grid as semitransparent and conductive electrode, obtaining a low PCE of 0.7%. The proposed approach to realize graphene-based electrodes could be a possible route to reduce the overall impact of the sheet resistance of this type of electrodes allowing their use in several optoelectronic devices.

HIT Solar Cell Modeling Using Graphene as a Transparent Conductive Layer Considering the Atacama Desert Solar Spectrum

“…However, the use of graphene instead of ITO decreased the efficiency of the cell in 13% for AM1.5. A similar result was obtained in the experimental work of Danietti et al [15]: they reported a decay of 30% when they used a graphene layer with a Niquel grid instead of ITO in organic cells. A similar decay was obtained in the experiment of Lancellotti et al [21], who used several graphene layers as AZO replacement in HIT cells.…”

“…Graphene has shown an interesting potential as a transparent conductor in several optoelectronic devices, such as LED, solar cells, touch screens, and so on [13,14]. Danietti et al [15] studied the incorporation of graphene as a transparent conductive layer in organic cells. For this purpose, they also included a Niquel grid below the graphene layer to enhance electrical conductivity.…”

A Review on the Materials Science and Device Physics of Semitransparent Organic Photovoltaics

“…Transparent conductive back electrodes, based on solution-processed metal nanowires [77,78], transferred doped graphene [4,79], conducting polymers [80], or their hybrids [81][82][83][84][85][86] are currently promising in the field of organic semitransparent photovoltaics, offering mild processing conditions that are compatible with the organic active layer materials. These electrodes exhibit very high transmittance within a wide spectral range and suitably low sheet resistance [87][88][89].…”