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  • Triple-halide wide-band gap perovskites with suppressed phase segregation for efficient tandems.

Triple-halide wide-band gap perovskites with suppressed phase segregation for efficient tandems.

Science (New York, N.Y.) (2020-03-07)
Jixian Xu, Caleb C Boyd, Zhengshan J Yu, Axel F Palmstrom, Daniel J Witter, Bryon W Larson, Ryan M France, Jérémie Werner, Steven P Harvey, Eli J Wolf, William Weigand, Salman Manzoor, Maikel F A M van Hest, Joseph J Berry, Joseph M Luther, Zachary C Holman, Michael D McGehee
ABSTRACT

Wide-band gap metal halide perovskites are promising semiconductors to pair with silicon in tandem solar cells to pursue the goal of achieving power conversion efficiency (PCE) greater than 30% at low cost. However, wide-band gap perovskite solar cells have been fundamentally limited by photoinduced phase segregation and low open-circuit voltage. We report efficient 1.67-electron volt wide-band gap perovskite top cells using triple-halide alloys (chlorine, bromine, iodine) to tailor the band gap and stabilize the semiconductor under illumination. We show a factor of 2 increase in photocarrier lifetime and charge-carrier mobility that resulted from enhancing the solubility of chlorine by replacing some of the iodine with bromine to shrink the lattice parameter. We observed a suppression of light-induced phase segregation in films even at 100-sun illumination intensity and less than 4% degradation in semitransparent top cells after 1000 hours of maximum power point (MPP) operation at 60°C. By integrating these top cells with silicon bottom cells, we achieved a PCE of 27% in two-terminal monolithic tandems with an area of 1 square centimeter.

MATERIALS
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