There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Silicon solar cells

Development of nanoparticle copper screen printing pastes for silicon heterojunction solar cells

High Efficiency Back-Contact Back-Junction Silicon Solar Cells with Cell Thicknesses of 45 μm, 90 μm, 130μm and 290 μm

Interdigitated back-contact (IBC) silicon (Si) solar cells are attracting increased attention due to the potential of higher efficiency that comes from eliminating front-surface shading. However, as sources of recombination loss continue to be reduced due to improved processing and use of high-quality n-type wafers, parasitic absorption in the rear metal can limit cell performance. This paper reports experimental and simulation results that identify the optical advantages of an IBC metallization method, which employs a novolac resin layer to enhance the insulation of the cell from a metal electrode comprising a sputtered Ti/Ag metal stack and plated Cu. The polymer layer can electrically decouple the metal geometry from the doping geometry and also helps to reduce the parasitic absorption at the cell rear surface by increasing the distance between the metal and Si absorber. The optical properties of the Ti/Ag stacks formed over the novolac resin were comparable to those with an Ag reflector; however, the Ti/Ag reflector offered the additional benefit of contact resistivity of < 1 mΩ·cm2 to both the n+ and p+ Si regions of the diffused IBC cells.

/pdf/metallization-method-for-interdigitated-back-contact-silicon-24cr8aonvn.pdf

Metallization Method for Interdigitated Back-Contact Silicon Solar Cells Employing an Insulating Resin Layer and a Ti/Ag/Cu Metal Stack

Patterning is fundamental to advancing most technologies. Although the challenge for electronic integrated circuits continues to be reduced feature size other applications have different requirements and challenges. This review contributes insights from silicon photovoltaics where patterning is required for selective doping etching and metallisation. Earlier silicon solar cell devices extensively used optical lithography to fabricate devices in the laboratory with high device efficiencies being achieved. However industrial cell fabrication has largely relied on uniformly doped silicon layers and lower resolution screen-printing for metal electrode formation because optical lithography is considered too expensive and slow. This has resulted in the average energy conversion efficiencies of industrially produced cells remaining on average 5% lower than the value of 25% reported in 1999 for cells patterned with optical lithography. Motivated by the goal of bridging this efficiency gap many new polymer pattern...

Z. Li

Papers

Patterned masking using polymers: insights and developments from silicon photovoltaics