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Illuminated Contact Resistivity Measurements to Investigate the Electrical Properties of Contact Stacks in Silicon Heterojunction Solar Cells
L.-L. Senaud, P.A. Procel Moya, G. Christmann, A. Descoeudres, J. Geissbühler, C. Allebé, N. Badel, P. Wyss, M. Boccard, O. Isabella, M. Zeman, S. Nicolay, M. Despeisse, C. Ballif, B. Paviet-Salomon
Silicon Materials and Cells
Subtopic: Low Temperature Route for Si Cells
Event: 37th European Photovoltaic Solar Energy Conference and Exhibition
Session: 2BO.5.3
ISBN: 3-936338-73-6
0,00 EUR
Document(s): presentation


The use of passivated contacts has been theoretically identified [1] and experimentally demonstrated [2, 3] to be the most promising way to reach the practical efficiency limit of single junction, crystalline silicon (c-Si) based solar cells. Yet, overcoming the remaining efficiency losses requires to improve the contacts selectivity [4] as well as mitigating the transport losses affecting the collection of photogenerated carriers [5]. In the specific case of the silicon heterojunction (SHJ) technology, we demonstrated in previous works the relevance of mixed-phase multi-layer stacks to fulfil these goals [6,7]. In this contribution, founded on a theoretical framework of transmission line method (TLM) measurements, we present a novel characterization methodology to investigate and assess the selectivity and the carrier transport quality in SHJ n-type contact stacks. More specifically, we demonstrate (i) how the dependence of the specific contact resistance () to a change in the carrier concentration within the c-Si wafer gives an indicator for the selectivity of a given SHJ ntype contact stack, and (ii) the importance of measuring under maximum power point (MPP) conditions. TCAD simulation was used to model a TLM structure and to identify physical phenomena and key parameters affecting the selectivity and of several SHJ n-type contact stacks. Then, we compare the simulation results with experimental data by performing TLM measurements under varying illuminations of the SHJ n-type contact stacks developed in [6,7], resulting in final both sides-contacted SHJ solar cells with 24.2% efficiency.