EPJ Photovoltaics 15, 34 (2024)
https://doi.org/10.1051/epjpv/2024030

Original Article

Influence of passivating interlayers on the carrier selectivity of MoO_x contacts for c-Si solar cells

¹ TNO Energy Transition Solar Energy, P.O. Box 15, NL-1755 ZG Petten, The Netherlands
² Delft University of Technology, PVMD group, Mekelweg 4, NL-2628 CD Delft, The Netherlands
³ AIKO Energy Netherlands B.V. (Eironn Netherlands B.V.), Schiphol Boulevard 201, Tower D6, 1118 BG Schiphol, The Netherlands

^* e-mail: m.t.s.k.ahsen@tudelft.nl

Received: 20 February 2024
Accepted: 4 September 2024
Published online: 21 October 2024

Abstract

The application of molybdenum oxide (MoO_x) as a hole-selective contact for silicon-based solar cells has been explored due to superior optical transmittance and potentially leaner manufacturing compared to fully amorphous silicon-based heterojunction (SHJ) devices. However, the development of MoO_x contacts has been hampered by their poor thermal stability, resulting in a carrier selectivity loss and an S-shaped IV curve. The aim of this study is to understand the influence of different passivating interlayers on the carrier selectivity of hole-selective MoO_x contacts for crystalline silicon (c-Si) solar cells. We highlight the effect of different interlayers on the surface passivation quality, contact selectivity, and the thermal stability of our MoO_x-contacted devices. The interlayers studied are intrinsic hydrogenated amorphous silicon (a-Si:H(i)), thermally grown ultrathin SiO₂, and a stack consisting of an ultrathin SiO_y and Al₂O₃ layer. Additionally, we simulate the interacting interlayer properties on the carrier selectivity of our MoO_x contacts using a simplified model. Among these interlayers, the Al₂O₃/SiO_y stack shows to be a promising alternative to SiO₂ by enabling efficient transport of holes while being able to sustain an annealing temperature of at least 250 °C underlining its potential in module manufacturing and outdoor operation.