51�������

Abstract:

Monolithic all-perovskite triple-junction solar cells have the potential to deliver power conversion efficiencies beyond those of state-of-art double-junction tandems and well beyond the detailed-balance limit for single junctions. Today, however, their performance is limited by large deficits in open-circuit voltage and unfulfilled potential in both short-circuit current density and fill factor in the wide-bandgap perovskite sub cell. Here we find that halide heterogeneity—present even immediately following materials synthesis—plays a key role in interfacial non-radiative recombination and collection efficiency losses under prolonged illumination for Br-rich perovskites. We find that a diammonium halide salt, propane-1,3-diammonium iodide, introduced during film fabrication, improves halide homogenization in Br-rich perovskites, leading to enhanced operating stability and a record open-circuit voltage of 1.44 V in an inverted (p–i–n) device; ~86% of the detailed-balance limit for a bandgap of 1.97 eV. The efficient wide-bandgap sub cell enables the fabrication of monolithic all-perovskite triple-junction solar cells with an open-circuit voltage of 3.33 V and a champion PCE of 25.1% (23.87% certified quasi-steady-state efficiency).

Abstract:

Wide-bandgap perovskites solar cells (PSCs) are vital as top cells in perovskite-based tandem solar cells (TSCs). However, poor band alignment with the charge transport layer and unwanted parasitic absorption in the top semitransparent-PSC (ST-PSC) are major factors limiting the power conversion efficiency (PCE) of TSCs. Herein, we present a compact-porous nickel oxide (cp-NiOx) hole-transport layer (HTL) sequentially fabricated using a sol-gel suspension and colloidal suspension of highly crystalline NiOx. The cp-NiOx film exhibited enhanced transparency, mesoporous surface morphology, and better energy band alignment with a 1.68 eV perovskite film for fabricating highly near-infrared transparent (∼92 % (@800–1200 nm)) ST-PSCs. The best cell achieved a PCE of 15.9 %. In addition, a four-terminal perovskite/silicon TSC based on the cp-NiOx HTL achieved an outstanding PCE of ∼26.0 %. The tailored energy band structure and reduced parasitic absorption in the near-infrared region of the ST-PSCs based on the cp-NiOx HTL enabled fabrication of highly efficient inverted ST-PSCs for perovskite/silicon TSCs.