Yohei Koi

High Efficiency Thin Film Silicon Hybrid Cell and Module with Newly Developed Innovative Interlayer

The paper discusses the development of a new light trapping scheme for a thin film Si based stacked cell and module, where a newly developed innovative interlayer is inserted between amorphous and microcrystalline Si thin film. This new interlayer leads intentional controlling of the refractive index of it. The interlayer with a lower refractive index of 1.7 at 600 nm exhibits both better reflection towards the top amorphous silicon cell and less absorption loss towards the bottom microcrystalline cell. We also proved by numerical simulation that the effect of the interlayer on light trapping towards the top cell is more enhanced with textured substrate. An initial cell efficiency of 15.0% has been achieved in a small area (1cm2) of its cell with this new interlayer. An initial aperture efficiency of 13.4% has been achieved for a 910times455 mm2 Si HYBRID PLUS module fabricated in a single chamber process of p-i-n microcrystalline cell, which was independently confirmed by AIST

High efficiency thin film silicon solar cell and module

An initial efficiency of 14.5% (Jsc=14.4mA/cm/sup 2/, Voc=1.41V, FF=71.9%) has been achieved for a-Si:H/transparent inter-layer/crystalline Si solar cell (total area of 1cm/sup 2/). Both a-Si and crystalline Si films were fabricated by plasma chemical vapor deposition at low temperature. The short circuit current (Jsc) was enhanced by the introduction of transparent interlayer without increasing the thickness of a-Si:H layer. An initial aperture efficiency of 12.3% has been achieved for 910/spl times/455mm/sup 2/ a-Si/crystalline Si thin film integrated solar cell module. Reasonably high deposition rate of 11 A/s for the deposition of crystalline Si for 1/spl times/1m/sup 2/ area has been achieved. By applying a deposition conditions of this high deposition rate, an initial aperture efficiency of 11.2% has been obtained above sized Si stacked solar cell module.

Thin film silicon solar cell and module

We have been developed a new light trapping scheme for thin film Si stacked module (Si HYBRID PLUS module), where a-Si:H/transparent inter-layer/microcrystalline Si thin film integrated large area solar cell module. An initial aperture efficiency of 13.1% has been achieved for 910/spl times/455 mm/sup 2/ Si HYBRID PLUS module, which was independently confirmed by AIST. This is the first time report for independently confirmed efficiency of large area thin film Si module with interlayer. The 19% increase of short circuit current (I/sub sc/) of this module was obtained by the introduction of transparent interlayer, namely internal light trapping. Stabilized efficiency of mini module exhibited the 12%. Outdoor performances of Si HYBRID (a-Si:H/micro-crystalline Si stacked) solar cell module have been investigated over 4 years for two different kind of modules (top and bottom cell limited, respectively). The Hybrid modules limited by the top cell have exhibited the more efficient performance rather than the bottom limited in natural sunlight at noon.