Description: Voltage-matched thin film solar cells in 3-terminal configuration

This title appears in the Scientific Report : 2018

Voltage-matched thin film solar cells in 3-terminal configuration

Multijunction solar cells, proven technological route for achievements of highest PV conversion efficiencierequire accurate tuning of the sub-cell absorption to ensure that every cell in the stack delivers the same currentdensity. Even though currents of the sub-cells can be precisely matched for a...

Personal Name(s):	Clemente de Lima, R.
	Merdzhanova, T. / Turan, B. / Kirchhoff, Joachim / Hüpkes, J. / Zahren, C. / Astakhov, O. (Corresponding author)
Contributing Institute:	Photovoltaik; IEK-5
Published in:	Solar energy materials & solar cells, 188 (2018) S. 202 - 209
Imprint:	Amsterdam [u.a.] NH, Elsevier 2018
DOI:	10.1016/j.solmat.2018.08.022
Document Type:	Journal Article
Research Program:	Solar cells of the next generation
	Publikationsportal JuSER

Please use the identifier: http://dx.doi.org/10.1016/j.solmat.2018.08.022 in citations.

Multijunction solar cells, proven technological route for achievements of highest PV conversion efficiencierequire accurate tuning of the sub-cell absorption to ensure that every cell in the stack delivers the same currentdensity. Even though currents of the sub-cells can be precisely matched for a fixed illumination spectrum,current mismatch cannot be avoided in real terrestrial applications due to variations of the irradiance spectrum.The issue becomes critical when a solar cell has to cover wider range of applications such as a mixture of directsun / shadow / artificial lightthe case for various distributed PV-powered electronics. Furthermore the current–matching constrains choice of materials and designs of sub-cells for a tandem device. A straightforward basicconfiguration with decoupling the sub-cell's currents is a 3-terminal configuration with one additional contactsheared by the top and bottom cell. This concept requires voltage-matching between the top and bottom cellwhen these cells are integrated in modules. A realistic concept for the voltage-matched 3-terminal cell reportedrecently includes a wide gap top cell combined with a tandem bottom cell made of 2 sub-cells with lowerbandgaps. The concept is a hybrid between 2 and 3-terminal configurations with voltage matching and relaxedcurrent matching constrains. Established thin film silicon solar cell technology provides interesting option torealize the hybrid 3-terminal cell with amorphous Si top cell(VOC0.9 V) and two microcrystalline Si cells(VOC0.5 V). In this work we present proof of concept of the voltage matched 3-terminal tandem cell prepared with˜highly transparent and conductive IOH intermediate contact. The efficiency of 10.4% has been achieved madeup of independently operating 7.9% efficient top cell and 2.5% efficient bottom tandem cell. The paper summarizesthe development and discusses optical losses identified in the 3-T devices.