Monolithic perovskite/c-Si tandem solar cells have attracted
enormous
research attention and have achieved efficiencies above 30%. This
work describes the development of monolithic tandem solar cells based
on silicon heterojunction (SHJ) bottom- and perovskite top-cells and
highlights light management techniques assisted by optical simulation.
We first engineered (i)a-Si:H passivating layers
for (100)-oriented flat c-Si surfaces and combined them with various
(n)a-Si:H, (n)nc-Si:H, and (n)nc-SiOx:H interfacial layers
for SHJ bottom-cells. In a symmetrical configuration, a long minority
carrier lifetime of 16.9 ms was achieved when combining (i)a-Si:H bilayers with (n)nc-Si:H (extracted at the
minority carrier density of 1015cm–3). The perovskite sub-cell uses a photostable mixed-halide composition
and surface passivation strategies to minimize energetic losses at
charge-transport interfaces. This allows tandem efficiencies above
23% (a maximum of 24.6%) to be achieved using all three types of (n)-layers. Observations from experimentally prepared devices
and optical simulations indicate that both (n)nc-SiOx:H and (n)nc-Si:H are promising
for use in high-efficiency tandem solar cells. This is possible due
to minimized reflection at the interfaces between the perovskite and
SHJ sub-cells by optimized interference effects, demonstrating the
applicability of such light management techniques to various tandem
structures.