Ligand Homogenized Br-I Wide-Bandgap Perovskites for Efficient NiOx-Based Inverted Semitransparent and Tandem Solar Cells.

Phase heterogeneity of bromine-iodine (Br-I) mixed wide-bandgap (WBG) perovskites has detrimental effects on solar cell performance and stability. Here, we report a heterointerface anchoring strategy to homogenize the Br-I distribution and mitigate the segregation of Br-rich WBG-perovskite phases. We find that methoxy-substituted phenyl ethylammonium (x-MeOPEA+) ligands not only contribute to the crystal growth with vertical orientation but also promote halide homogenization and defect passivation near the buried perovskite/hole transport layer (HTL) interface as well as reduce trap-mediated recombination. Based on improvements in WBG-perovskite homogeneity and heterointerface contacts, NiOx-based opaque WBG-perovskite solar cells (WBG-PSCs) achieved impressive open-circuit voltage (Voc) and fill factor (FF) values of 1.22 V and 83%, respectively. Moreover, semitransparent WBG-PSCs exhibit a PCE of 18.5% (15.4% for the IZO front side) and a high FF of 80.7% (79.4% for the IZO front side) for a designated illumination area (da) of 0.12 cm2. Such a strategy further enables 24.3%-efficient two-terminal perovskite/silicon (double-polished) tandem solar cells (da of 1.159 cm2) with a high Voc of over 1.90 V. The tandem devices also show high operational stability over 1000 h during T90 lifetime measurements.

Crystallization Kinetics of Perovskite Films by a Green Mixture Antisolvent for Efficient NiOx-Based Inverted Solar Cells.

Environment-friendly antisolvents are critical for obtaining highly efficient, reproducible, and sustainable perovskite solar cells (PSCs). Here, we introduced a green mixture antisolvent of ethyl acetate-isopropanol (EA/IPA) to finely regulate the crystal grain growth and related film properties, including the morphology, crystal structure, and chemical composition of the perovskite thin film. The IPA with suitable content in EA plays a key role in achieving a smooth and compact high-quality perovskite thin film, leading to the suppression of film defect-induced nonradiative recombination. As a result, the PSCs based on the EA/IPA (5:1) antisolvent showed a power conversion efficiency of 22.9% with an open-circuit voltage of 1.17 V.

Over 10% Efficient Sb2 (S,Se)3 Solar Cells Enabled by CsI-Doping Strategy.

Antimony selenosulfide (Sb2 (S,Se)3 ) is an emerging quasi-1D photovoltaic semiconductor with exceptional photoelectric properties. The low-symmetry chain structure contains complex defects and makes it difficult to improve electrical properties via doping method. This article reports a doping strategy to enhance the efficiency of Sb2 (S,Se)3 solar cells by using alkali halide (CsI) as the hydrothermal reaction precursor. It is found that the Cs and I ions are effectively doped and atomically coordinate with Sb ions and S/Se ions. The CsI-doping Sb2 (S,Se)3 absorbers exhibit enhanced grain morphologies and reduced trap densities. The consequential CsI-doping Sb2 (S,Se)3 based solar cells demonstrate favorable band alignment, suppressed carrier recombination, and improved device performance. An efficiency as high as 10.05% under standard AM1.5 illumination irradiance is achieved. This precursor-based alkali halide doping strategy provides a useful guidance for high-efficiency antimony selenosulfide solar cells.

Back Contact Interfacial Modification in Highly-Efficient All-Inorganic Planar n-i-p Sb2Se3 Solar Cells.

Sb2Se3 is an emerging and promising light-absorbing material with superior photovoltaic properties. However, the specific one-dimensional structure of Sb2Se3 limits the doping density, preventing a high built-in potential. Moreover, in the superstrate devices the back contact is often non-ohmic. In this work, we have successfully applied tungsten oxide (WO3-x) as a hole-transport layer in superstrate n-i-p Sb2Se3 solar cells. It is found that an interfacial dipole is formed at Sb2Se3/WO3-x interface via Sb-W bonds, which reduces the barrier for hole extraction. Meantime, gap states are present at a suitable energy level to serve as intermediate states for hole-transport from the Sb2Se3 absorber to the metal anode. In addition, the introduction of WO3-x can suppress carrier recombination at the back interface, enhance the built-in potential, and improve the spectral response in the long-wavelength region. Consequently, the superstrate devices with the incorporated WO3-x layer achieve a champion efficiency of 7.10% due to the enhancement of all device parameters. Furthermore, the all-inorganic devices with WO3-x hole-transport layer exhibit excellent air stability and thermal stability.