Nanoimprint Lithography as a Route to Nanoscale Back-Contact Perovskite Solar Cells

Back-contact perovskite solar cells are of great interestbecausethey could achieve higher performance than conventional designs whilealso eliminating the need for transparent conductors. Current researchin this field has focused on making electrode structures with reducedwidths to collect charges more efficiently, but current lift-off-basedfabrication techniques have struggled to achieve electrode widthssmaller than 1000 nm and are difficult to implement on large areas.We demonstrate nanoimprint lithography in an etch-down procedure asa simple and easily scalable method to produce honeycomb-shaped, quasi-interdigitatedelectrode structures with widths as small as 230 nm. We then use electrodepositionto selectively deposit conformal coatings of a range of differenthole-selective layers and explore how the efficiency of back-contactperovskite solar cells changes as the feature sizes are pushed intothe nanoscale. We find that the efficiency of the resulting devicesremains almost unchanged as the electrode width is varied from 230to 2000 nm, which differs from reported device simulations. Our resultssuggest that reducing recombination and improving the quality of thecharge transport layers, rather than reducing the minimum featuresize, are likely to be the best pathway to maximizing the performanceof back-contact perovskite solar cells.

Automated summary

This study demonstrates the use of nanoimprint lithography to fabricate honeycomb-shaped, quasi-interdigitated electrode structures for back-contact perovskite solar cells. The efficiency of the resulting devices remains almost unchanged as the electrode width is varied from 230 to 2000 nm, suggesting that improving the quality of charge transport layers and reducing recombination are more important for maximizing the performance of these solar cells than reducing the minimum feature size.