Two Anthracene-Based Copolymers as the Hole-Transporting Materials for High-Performance Inverted (p-i-n) Perovskite Solar Cells

Two anthracene-based copolymers, the thiophene-bridged carbazole-anthracene copolymer (abbreviated as <b>PCBZANT</b>) and the thiophene-bridged triphenylamine-anthracene copolymer (abbreviated as <b>PTPAANT</b>), have been developed as the hole-transporting materials (HTMs) for the inverted perovskite solar cells. They were thermally stable with decomposition temperatures of 435 and 420 °C. The High Occupied Molecular Orbitals (HOMO) of −5.15 and −5.24 eV of two copolymers facilitated the hole carriers transfer from the perovskite layer (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>, HOMO: −5.4 eV) in contrast to poly­(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS, HOMO: −4.9 eV). The solar cell with <b>PCBZANT</b> (abbreviated as the <b>PCBZANT</b> device) showed the highest power conversion efficiency (PCE) of 15.50%, while the cell with <b>PTPAANT</b> (abbreviated as the <b>PTPAANT</b> device) showed the highest PCE of 14.52%, with increases of 36.2% and 27.6%, respectively, relative to the PEDOT:PSS device. The thorough analysis disclosed that the high performance was mainly ascribed to the enhanced open-circuit voltage (<i>V</i><sub>OC</sub>) and short-circuit current density (<i>J</i><sub>SC</sub>), being contributed from the efficient hole-carrier extraction, the high hole mobility of two copolymers, and the high-quality perovskite film with large crystal size and less defect. With strong absorption in the range of 350–500 nm, the polymers decreased the destruction of UV-radiation on the perovskite layer as UV-filters and improved the stability of the inverted cells.