Dandan Chen,Fengxia Yang,Mei Yang,Wenming Chai,Weidong Zhu,Chunfu Zhang,Yun Zhao,Yan Li
Perovskite and Cu(InGa)Se 2 (CIGS) tandem solar cells are emerging as an exciting prospect to achieve high-performance, cost effective, and lightweight all-thin-film photovoltaics, wherein perovskite solar cells (PSCs) fabricated using high-quality wide-bandgap perovskite films are critical to realize the high-efficiency PSC/CIGS tandem solar cells. Herein, a stepwise dimethyl sulfoxide (DMSO) solvent-annealing strategy is proposed to fabricate wide-bandgap (1.68 eV) Cs 0.15 FA 0.65 MA 0.2 PbI 2.4 Br 0.6 films via stepwise heating recipe, that is annealed at 100 °C firstly and then 80 °C. This modified solvent-annealing method makes for the Cs 0.15 FA 0.65 MA 0.2 PbI 2.4 B r0.6 films with full coverage, large grains, improved crystallinity, and free of impurities. Opaque PSCs with the desired Cs 0.15 FA 0.65 MA 0.2 PbI 2.4 B r0.6 films exhibit a champion power conversion efficiency (PCE) of 21.66 % and excellent stability. Furthermore, using an optimized IZO transparent electrode, the semitransparent PSCs with an impressive PCE of 21.26 % and a high bifaciality factor of 92.2 % are fabricated. These PSCs can further enable the four-terminal (4-T) PSC/CIGS tandem solar cells with a summed PCE of 29.36 %, surpassing of most the similar tandem solar cells reported earlier.
Block copolymer (BCP) films with perpendicularly aligned cylindrical domains of high aspect ratio have important applications in diverse fields. However, an aspect ratio of the cylinders as high as 200 has rarely been reported so far. Here we demonstrate an efficient route to the formation of normally aligned P4VP cylinders with high aspect ratio surrounded by a matrix of azobenzene-containing block (PMA(Az)) via hierarchical self-assembly. A crisscross structure, consisting of parallelly aligned liquid crystalline (LC) layers and normally aligned self-assembly domains, is expected to assist the formation of well-defined nanostructures. The LC layers in the cylindrical films self-assemble to form smectic phase after solvent annealing, as confirmed by WAXD and UV-vis spectra. We found that the aspect ratio of the vertical P4VP cylinders is up to 200 and the film thickness reaches 6 μm. P4VP is a functional polymer, making this P4VP-b-PMA(Az) film more suitable for advanced filters, multi-nanochannels, nanolithography, and high-density storage media, etc.