Hole-transporting materials (HTMs) are essential for enabling highly efficient perovskite solar cells (PVSCs) to extract and transport the hole carriers. Among numerous HTMs that have been studied so far, the single-spiro based compounds are the most frequently used HTMs for achieving highly efficient PVSCs. In fact, all the new spiro-based HTMs reported so far that render PVSCs over 20% are based on spiro[fluorene-9,9'-xanthene] or spiro [cyclopenta [2,1-b:3,4b']dithiophene-4,9'fluorene] cores, therefore there is a need in diversifying the design of their structures for further improving their function and performance. In addition, the fundamental understanding of structureperformance relationships for the spiro-based HTMs is still lagging, for example, how molecular configuration, spiro numbers and heteroatoms in spiro rings impact the efficacy of HTMs. To address these needs, two novel H-shaped HTMs, G1 and G2 based on the di-spiro rings as the cores are designed and synthesized. The combined good film-forming properties, better interactions with perovskite, slightly deeper HOMO, higher mobility and conductivity, as well as more efficient charge transfer for G2 help devices reach a very impressive power conversion efficiency (PCE) of 20.2% and good stability. This is the first report of demonstrating the feasibility of using di-spiro based HTMs for highly efficient PVSCs.

With water as an eco-friendly heterogeneous nucleation accelerator, silver nanowires (Ag NWs) have been successfully prepared with a high aspect ratio (>1600). The Ag NW-based film exhibits a low sheet resistance of 8.1 U sq À1 with a transparency of 81.9% at 550 nm, showing the potential application of electrode materials in polymer solar cells. † Electronic supplementary information (ESI) available: Process of slot-die coating inverted OSCs with Ag NWs electrode; morphology the core-shell structure of Ag NWs made by PVP of high molecular weight; the performance of TCFs made from different Ag NWs; the aspect ratio of Ag NWs made by different polyol method. See

No abstract