Lang, F.; Gluba, M.A.; Albrecht, S.; Shargaieva, O.; Rappich, J.; Korte, L.; Rech, B.; Nickel, N.H.: Front cover : In situ graphene doping as a route toward efficient perovskite tandem solar cells. Physica Status Solidi A 213 (2016), p. 1629
10.1002/pssa.201670643
Abstract:
The development of silicon solar cells gradually approaches the theoretical effi ciency limit. Therefore, achieving improvements becomes ever more challenging. A promising strategy is the combination of silicon and perovskite absorbers in a tandem device. Their complementary band gaps reduce thermalization losses of high-energy photons. However, the perovskite top solar cell requires a suitable transparent electrode that can be gently deposited on its organic layers. Being the topmost layer this electrode must be highly transparent in the visible and near-IR part of the electromagnetic spectrum. An excellent candidate for this electrode is large-area graphene obtained by chemical vapour deposition. Up to now the low charge-carrier density in graphene constrained the electrical properties of the solar cells. In their study F. Lang et al. (pp. 1983–1990) explored various organic layers to increase the charge-carrier density of graphene by in-situ fi eld-effect doping while maintaining high charge-carrier mobilities. The authors successfully implemented graphene into perovskite top solar cells yielding state-of-the-art open circuit voltages of about 1 V and charge collection effi ciencies exceeding 77%.