Research on electronic and structural properties of amorphous-silicon-based alloy materials. Annual subcontract report, July 1984-June 1985

Hydrogenated amorphous silicon (a-Si:H) has been developed as an important materials in thin film-based photovoltaic technologies because of considerable cost reduction as a result of low material consumption and low-temperature process. Among the materials used for thin film solar cells, amorphous silicon is the most important material in the commercial production. Despite of these benefits, the efficiency limit for a single band gap thin film based solar cell predicted by Shockley and Queisser (i.e. ~31%) has become a matter of challenge for current research community. Considering the thermodynamic behavior of a single threshold absorber in generating electricity from solar irradiance, this limit seems inevitable, and thus a tremendous investigation is now being carried out in different dimensions such as hot carrier generation, rainbow solar cell, multiple exciton generation, multiband absorber etc. Nonetheless, so far reported efficiency (ηlab~12%) provide enough room to improve and take challenge to reach to the highest value for a-Si:H based solar cell design. Further to improve architectural design as well as engineer the materials, it is indispensable to understand the optical, electrical and structural properties of aSi:H as an active layer. Here in this article, an attempt was taken into account to focus on such characteristics that affect the overall cell efficiency.

Download Full-text

Use of Transparent Conductive Oxide Materials with Low Indices of Refraction in Amorphous Silicon-Based Solar Cell Technology

MRS Proceedings ◽

10.1557/proc-862-a21.1 ◽

2005 ◽

Vol 862 ◽

Author(s):

Scott J. Jones ◽

Joachim Doehler ◽

Tongyu Liu ◽

David Tsu ◽

Jeff Steele ◽

...

Keyword(s):

Solar Cell ◽

Amorphous Silicon ◽

Transparent Conductive Oxide ◽

Open Circuit ◽

Long Term Stability ◽

Back Reflectors ◽

Stability Issues ◽

Silicon Based ◽

Solar Cell Technology

AbstractNew types of transparent conductive oxides with low indices of refraction have been developed for use in optical stacks for the amorphous silicon (a-Si) solar cell and other thin film applications. The alloys are ZnO based with Si and MgF added to reduce the index of the materials through the creation of SiO2 or MgF2, with n=1.3-1.4, or the addition of voids in the materials. Alloys with 12-14% Si or Mg have indices of refraction at λ=800nm between 1.6 and 1.7. These materials are presently being used in optical stacks to enhance light scattering by Al/multi-layer/ZnO back reflectors in a-Si based solar cells to increase light absorption in the semiconductor layers and increase open circuit currents and boost device efficiencies. In contrast to Ag/ZnO back reflectors which have long term stability issues due to electromigration of Ag, these Al based back reflectors should be stable and usable in manufactured PV products. In this manuscript, structural properties for the materials will be reported as well as the performance of solar cell devices made using these new types of materials.

Download Full-text