Revealing Fundamental Efficiency Limits of Monolithic Perovskite/Silicon Tandem Photovoltaics through Subcell Characterization

Abstract

Perovskite/silicon tandem photovoltaics (PVs) promise to accelerate the decarbonization of our energy systems. Here, we present a thorough subcell diagnosis methodology to reveal deep insights into the practical efficiency limitations of state-of-the-art perovskite/silicon tandem PVs. Our subcell selective intensity-dependent photoluminescence (PL) and injection-dependent electroluminescence (EL) measurements allow independent assessment of pseudo-V OC and power conversion efficiencies (PCEs) for both subcells. We reveal identical metrics from PL and EL, which implies well-aligned energy levels throughout the entire cell. Relatively large ideality factors and insufficient charge extraction, however, cause each a fill factor penalty of about 6% (absolute). Using partial device stacks, we then identify significant losses in standard perovskite subcells due to bulk and interfacial recombination. Lastly, we present strategies to minimize these losses using triple halide (CsFAPb­(IBrCl)3) based perovskites. Our results give helpful feedback for device development and lay the foundation toward advanced perovskite/silicon tandem PVs capable of exceeding 33% PCE.

Monolithic Perovskite/Silicon Tandem Solar Cells Fabricated Using Industrial p‐Type Polycrystalline Silicon on Oxide/Passivated Emitter and Rear Cell Silicon Bottom Cell Technology

“…[ 25 ] Then, we spin coat the perovskite precursor layer, followed by an annealing step that leads to the formation of the photoactive perovskite crystal structure. Here, we use a triple‐halide CsFAPb(IBrCl) 3 perovskite composition, similar to that reported by Xu et al [ 26 ] and Lang et al, [ 27 ] with a bandgap of 1.68 eV. While we use a spin‐speed of 5000 rpm for the fabrication of perovskite single junctions, we adjusted the concentration to 1.4 m and the spin speed from 3500 to 5000 rpm when spin coating on bottom cells, to fine tune the average thickness of the wrinkled perovskite layer from roughly 560 nm to 470 nm to drive the current density of the top cell closer to current matching with the planar bottom cell (see Figure S2.1, Supporting Information).…”

Efficient and stable perovskite-silicon tandem solar cells through contact displacement by MgF x

“…Then the pseudo JV curves of the two sub-cells are numerically summed to obtain the final pseudo JV curves. Following previously established processes (43), the approach explained below is used to calculate quantum efficiency of electroluminescence (EQEEL) and extract the quasi-Fermi level splitting (QFLSEL) of perovskite subcells. EQEEL is define as the ratio of radiative recombination current (Jrad) to injection current (Jinj).…”

“…Fig. S1 to S27Tables S1 References(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56) …”

Nano-optical designs enhance monolithic perovskite/silicon tandem solar cells toward 29.8% efficiency

“…From the emitted EL, we calculated the quasi-Fermi level splitting (QFLS EL ). The injection-dependent QFLS EL equals a series-resistance-free dark JV curve, from which we can generate a pseudo-JV curve by adding the generation current 35,36 . Figure 4c shows the obtained characteristics of both subcells in the tandem configuration for the planar and nanotextured PSTSC.…”