Doped but Stable: Spirobisacridine Hole Transporting Materials for Hysteresis-Free and Stable Perovskite Solar Cells
摘要:
Four spirobisacridine (SBA) hole-transporting materials were synthesized and employed in perovskite solar cells (PSCs). The molecules bear electronically inert alkyl chains of different length and bulkiness, attached to in-plane N atoms of nearly orthogonal spiro-connected acridines. Di-p-methoxyphenylamine (DMPA) substituents tailored to the central SBA-platform define electronic properties of the materials mimicking the structure of the benchmark 2,2',7,7'-tetrakis(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene (spiro-MeOTAD), while the alkyl pending groups affect molecular packing in thin films and affect the long-term performance of PSCs. Devices with SBA-based hole transporting layers (HTL) attain efficiencies on par with spiro-MeOTAD. More importantly, solar cells with the new HTMs are hysteresis-free and demonstrate good operational stability, despite being doped as spiro-MeOTAD. The best performing MeSBA-DMPA retained 88% of the initial efficiency after a 1000 h aging test under constant illumination. The results clearly demonstrate that SBA-based compounds are potent candidates for a design of new HTMs for PSCs with improved longevity.
在此,利用廉价易得的苯甲醛和丙酮作为起始原料,以及(1 R ,2 R )-或(1 S , 2 S )-1,2-二苯基乙烷-1,2-二醇作为可回收的手性拆分试剂。R-和S的进一步转化通过合成路线的合理设计和聚合条件的优化,实现了-1,1'-螺二茚满-3,3'-二酮转化为手性单体和聚合物。所得的手性光学聚合物表现出具有热激活延迟荧光(TADF)的蓝色发射、具有高达6.4×10 -3的圆二色性强度/摩尔吸收系数(gabs )的优异光学活性以及具有发光的强烈圆偏振发光(CPL)不对称因子 ( g lum ) 值高达 2.4 × 10 -3。