Highly Efficient Perovskite–Perovskite Tandem Solar Cells Reaching 80% of the Theoretical Limit in Photovoltage

5 years ago

Highly Efficient Perovskite–Perovskite Tandem Solar Cells Reaching 80% of the Theoretical Limit in Photovoltage

Po-Wei Liang, Zhibin Yang, Sae Byeok Jo, Hugh W. Hillhouse, Adharsh Rajagopal, Alex K.-Y. Jen, Ian L. Braly

Organic–inorganic hybrid perovskite multijunction solar cells have immense potential to realize power conversion efficiencies (PCEs) beyond the Shockley–Queisser limit of single-junction solar cells; however, they are limited by large nonideal photovoltage loss (V oc,loss) in small- and large-bandgap subcells. Here, an integrated approach is utilized to improve the V oc of subcells with optimized bandgaps and fabricate perovskite–perovskite tandem solar cells with small V oc,loss. A fullerene variant, Indene-C60 bis-adduct, is used to achieve optimized interfacial contact in a small-bandgap (≈1.2 eV) subcell, which facilitates higher quasi-Fermi level splitting, reduces nonradiative recombination, alleviates hysteresis instabilities, and improves V oc to 0.84 V. Compositional engineering of large-bandgap (≈1.8 eV) perovskite is employed to realize a subcell with a transparent top electrode and photostabilized V oc of 1.22 V. The resultant monolithic perovskite–perovskite tandem solar cell shows a high V oc of 1.98 V (approaching 80% of the theoretical limit) and a stabilized PCE of 18.5%. The significantly minimized nonideal V oc,loss is better than state-of-the-art silicon–perovskite tandem solar cells, which highlights the prospects of using perovskite–perovskite tandems for solar-energy generation. It also unlocks opportunities for solar water splitting using hybrid perovskites with solar-to-hydrogen efficiencies beyond 15%. High open-circuit voltage, V oc (1.98 V) and power conversion efficiency, PCE (18.5%) is realized in an ideal bandgap-matched two-terminal perovskite–perovskite tandem solar cell via an integrated approach. A fullerene variant, Indene-C60 bis-adduct is used to achieve optimized interfacial contact and alleviate hysteresis instabilities in the small-bandgap subcell. Compositional engineering is employed to realize more highly photostabilized V oc in the large-bandgap subcell.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201702140