Fully screen‐printed silicon solar cells with local Al‐p⁺ and n‐type POLO interdigitated back contacts with a V_OC of 716 mV and an efficiency of 23%

authored by

Felix Haase, Byungsul Min, Christina Hollemann, Jan Krügener, Rolf Brendel, Robby Peibst

Abstract

We demonstrate the fabrication of a fully screen‐printed p‐type silicon solar cell with local hole‐collecting Al‐alloyed (Al‐p+) contacts with a record open circuit voltage of 716 mV. The solar cell is fabricated by using almost the same process equipment as PERC cells. One of the dominant recombination losses in PERC cells is the recombination in the passivated and in the contacted emitter regions that so far limit the open circuit voltage to values below 700 mV. We eliminate these loss channels by substituting the P‐diffused emitter by a passivating n‐type poly‐Silicon on Oxide (nPOLO) contact. We place this contact on the rear side because of its otherwise strong parasitic absorption. The Al‐p+ contacts are also located at the rear side to avoid front‐side shading. This results in a POLO‐IBC cell structure. The efficiency of the best cell so far is 23.0% with a designated area of 4 cm2 fabricated on a M2‐sized wafer. Scanning electron microscopy reveals an Al‐p+ thickness of less than 3.3 μm and only a few 100 nm at the contact ends, which is less than the 5 μm typically for optimized Al‐p+ contacts. A comparison of measured and simulated current‐voltage curves over a variation of the contact fraction extracts a high saturation current density of the Al‐p+ contact of J0‐Al ‐p+ = 2,250 fA cm−2 for the current screen‐print conditions and Al‐paste causing an absolute efficiency loss of 0.5%abs. The recombination at the AlOx/SiNy surface and the shunt resistance limits the cell by 0.6%abs each.

Organisation(s)

Institute of Electronic Materials and Devices
Laboratory of Nano and Quantum Engineering
Solar Energy Section

External Organisation(s)

Institute for Solar Energy Research (ISFH)

Type

Article

Journal

Progress in Photovoltaics: Research and Applications

Volume

29

Pages

516-523

No. of pages

8

ISSN

1062-7995

Publication date

15.04.2021

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Electronic, Optical and Magnetic Materials, Condensed Matter Physics, Electrical and Electronic Engineering, Renewable Energy, Sustainability and the Environment

Sustainable Development Goals

SDG 7 - Affordable and Clean Energy

Electronic version(s)

https://doi.org/10.1002/pip.3399 (Access: Closed)