Tandem cells (combining silicon and perovskite nanocrystals) have a larger bandgap than silicon and capture more of the solar spectrum for energy generation.

Singlet fission produces twice the electronic charge carriers than normal for each photon of light that's absorbed. Tetracene is used in these devices to transfer the energy generated by singlet fission into silicon.

Abstract
The economic value of a photovoltaic installation depends upon both its lifespan and power conversion efficiency. Progress toward the latter includes mechanisms to circumvent the Shockley?Queisser limit, such as tandem designs and multiple exciton generation (MEG). Here we explain how both silicon tandem and MEG?enhanced silicon cell architectures result in lower cell operating temperatures, increasing the device lifetime compared to standard c?Si cells. Also demonstrated are further advantages from MEG enhanced silicon cells: (i) the device architecture can completely circumvent the need for current?matching; and (ii) upon degradation, tetracene, a candidate singlet fission (a form of MEG) material, is transparent to the solar spectrum. The combination of (i) and (ii) mean that the primary silicon device will continue to operate with reasonable efficiency even if the singlet fission layer degrades. The lifespan advantages of singlet fission enhanced silicon cells, from a module perspective, are compared favorably alongside the highly regarded perovskite/silicon tandem and conventional c?Si modules.