Metal nano-grids for transparent conduction in solar cells

Abstract

2017-08-25T16:29:28

Materials for Transparent Electrodes: From Metal Oxides to Organic Alternatives

“…[83] Furthermore it has been demonstrated that the discontinuous character of the electrode induces an increase in resistance in the neighboring semiconducting layer, which is why different criteria than the commonly used FoM should be considered for the evaluation of metal grid electrodes. [84] Upon optimization of the pattern dimensions, films with a sheet resistance between 5 Ohm sq -1 to 24 Ohm sq -1 with 70% to 80% transmittance (FoM between 60 and 190) in the visible range can be obtained. [85][86][87] Photovoltaic cells based on such metal grid electrodes exhibited the same performance as ITO reference cells.…”

Understanding Printed Hexagonal Contacts for Large Area Solar Cells through Simulation and Experiments

“…Although previously many different semitransparent contact structures have been proposed, [ 15 ] within this work, we focused on hexagonal silver contacts because they have been used widely in organic electronics due to their ability to geometrically pack efficiently. The substrate used for the fabrication process was a 125 μm‐thick polyethylene terephthalate (PET) roll (Melinex 506) purchased from DuPont Teijin Films.…”

Comment on “Introduction of a Novel Figure of Merit for the Assessment of Transparent Conductive Electrodes in Photovoltaics: Exact and Approximate Form”

“…On the other hand, previous work has shown that lumping series resistance externally yields an exact, explicit equation for TCE merit. [ 5–7 ] For example, a uniform TCE applied to a solar cell operating at its MP point with current density ( J MP ) and voltage ( V MP ) would reduce its current and voltage to J MP,TCE and V MP,TCE $$\[ \begin{array}{*{20}{c}}{{J_{{\rm{MP,TCE}}}} = {J_{{\rm{MP}}}} \cdot {T_{{\rm{TCE,avg}}}}}\end{array} \]$$ $$\[ \begin{array}{*{20}{c}}{{V_{{\rm{MP,TCE}}}} = {V_{{\rm{MP}}}} - {R_{{\rm{TCE}}}} \cdot A \cdot {J_{{\rm{MP}}}} = {V_{{\rm{MP}}}} - \frac{{{R_{{\rm{sh,TCE}}}} \cdot {L^2} \cdot {J_{{\rm{MP}}}}}}{3}}\end{array} \]$$…”

“…[ 1,14 ] However, metal grids have nonuniformity that induces resistance in the underlying semiconductor, so their merit deviates from that of uniform TCEs. [ 6 ] Therefore, coupling a uniform TCE with a metal grid changes TCE merit. For example, the metal grating in Figure 1c has a transmittance of T grid = s /( s + w ), and the sheet resistance of a grating with ρ metal resistivity and h metal height is R sh,grid = ρ metal · ( s + w )/( w · h metal ).…”

“…For example, the metal grating in Figure 1c has a transmittance of T grid = s /( s + w ), and the sheet resistance of a grating with ρ metal resistivity and h metal height is R sh,grid = ρ metal · ( s + w )/( w · h metal ). Such a grid changes resistance in the TCE to R TCE,grid while adding resistance in the grid ( R grid ) [ 6 ] $$\[ \begin{array}{*{20}{c}}{{R_{{\rm{TCE,grid}}}} = \frac{{{R_{{\rm{sh,TCE}}}} \cdot {s^2}}}{{12 \cdot A}} = \frac{{{R_{{\rm{sh,TCE}}}} \cdot T_{{\rm{grid}}}^2 \cdot {w^2}}}{{12 \cdot A \cdot {{\left( {1 - {T_{{\rm{grid}}}}} \right)}^2}}}}\end{array} \]$$ $$\[ \begin{array}{*{20}{c}}{{R_{{\rm{grid}}}} = \frac{{{R_{{\rm{sh,grid}}}} \cdot {L^2}}}{{3 \cdot A}} = \frac{{{\rho _{{\rm{metal}}}} \cdot {L^2}}}{{3 \cdot A \cdot {h_{{\rm{metal}}}} \cdot \left( {1 - {T_{{\rm{grid}}}}} \right)}} = \frac{{{\rho _{{\rm{metal}}}} \cdot {L^2} \cdot \left( {s + w} \right)}}{{3 \cdot A \cdot {h_{{\rm{metal}}}} \cdot w}}}\end{array} \]$$…”