Wagner, P.; Tockhorn, P.; Hall, S.; Albrecht, S.; Korte, L.: Performance of Monolithic Two and Three Terminal Perovskite Silicon Tandem Solar Cells Under Varying Illumination Conditions. Solar RRL 7 (2023), p. 2200954/1-10
10.1002/solr.202200954
Open Access Version
Abstract:
Research on perovskite/silicon tandem solar cells is chiefly focussed on devices in either two or four terminal configuration (2T and 4T respectively). Straying from these commonly investigated approaches, we present an alternative monolithically integrated device architecture using three terminals (3T) by combining a semi-transparent perovskite top cell with a silicon heterojunction bottom cell featuring interdigitated rear contacts. We demonstrate that for the presence of a p/n recombination junction between sub-cells, a quasi-2T configuration is obtained where the additional terminal functions as a current regulator. Thus, in contrast to 2T tandems, current matching between sub-cells is not necessary. This makes these devices more stable against spectral variations, especially its voltages at maximum-power point, as surplus current can be either injected into or extracted from the additional terminal, which is tested both by simulations and for the first time experimentally. Interestingly, the highest power conversion efficiency (PCE) is not achieved by current matching but by maximising current generation in the top cell. We present an experimental realisation of a 3T tandem with p/n recombination junction and a PCE of 24.9%, thus confirming the general viability of the concept.