3D Conjugated Hole Transporting Materials for Efficient and Stable Perovskite Solar Cells and Modules

The orthogonal structure of the widely used hole transporting material (HTM) 2,2 ',7,7 '-tetrakis(N, N-di-p-methoxyphenylamino)-9,9 '-spirobifluorene (Spiro-OMeTAD) imparts isotropic conductivity and excellent film-forming capability. However, inherently weak intra- and inter-molecular pi-pi interactions result in low intrinsic hole mobility. Herein, a novel HTM, termed FTPE-ST, with a twist conjugated dibenzo(g,p)chrysene core and coplanar 3,4-ethylenedioxythiophene (EDOT) as extended donor units, is designed to enhance pi-pi interactions, without compromising on solubility. The three-dimensional (3D) configuration provides the material multi-direction charge transport as well as excellent solubility even in 2-methylanisole, and its large conjugated backbone endows the HTM with a high hole mobility. Moreover, the sulfur donors in EDOT units coordinate with lead ions on the perovskite surface, leading to stronger interfacial interactions and the suppression of defects at the perovskite/HTM interface. As a result, perovskite solar cells (PSCs) employing FTPE-ST achieve a champion power conversion efficiency (PCE) of 25.21% with excellent long-time stability, one of the highest PCEs for non-spiro HTMs in n-i-p PSCs. In addition, the excellent film-forming capacity of the HTM enables the fabrication of FTPE-ST-based large-scale PSCs (1.0 cm2) and modules (29.0 cm2), which achieve PCEs of 24.21% (certificated 24.17%) and 21.27%, respectively.|A novel 3D hole transporting material termed FTPE-ST is reported, which has a large conjugated structure leading to high hole mobility, and sulfur atoms that can bind to coordinately unsaturated lead centers on the surface of perovskite films, enhancing interfacial interactions. Perovskite solar cells and modules incorporating FTPE-ST achieve power conversion efficiencies of 25.21 and 21.27%, respectively. image