A new strategy for constructing a dispiro-based dopant-free hole-transporting material: spatial configuration of spiro-bifluorene changes from a perpendicular to parallel arrangement

Abstract

Due to the low intrinsic hole mobility caused by orthogonal conformation of two fluorene units in Spiro-OMeTAD which is a classic hole-transporting material (HTM) in perovskite solar cells (PSCs), Spiro-OMeTAD...

Efficient and Stable Methylammonium-Free Tin-Lead Perovskite Solar Cells with Hexaazatrinaphthylene-Based Hole-Transporting Materials

“…The hole mobility of TPA-HATNA was 1.47 × 10 –4 cm 2 V –1 s –1 , lower than that of MeOTPA-HATNA (4.09 × 10 –4 cm 2 V –1 s –1 ), which could be connected with the interactions brought by surplus methoxy groups. Therefore, the HATNA derivatives possess a promising hole-transporting capacity, which allows them to become effective HTMs in Sn-Pb PSCs without extra dopants. , …”

“…Therefore, the HATNA derivatives possess a promising hole-transporting capacity, which allows them to become effective HTMs in Sn-Pb PSCs without extra dopants. 25,26 The remaining incident light through the HTMs in p-i-n devices can be captured by the absorbers. Especially for Sn-Pb perovskites, the capture of long-wavelength light is particularly critical.…”

Recent advances in dopant-free organic hole-transporting materials for efficient, stable and low-cost perovskite solar cells

“…Additionally, inspired by the classic Spiro-OMeTAD, Jia and Wang et al designed a dispiro-based dopant-free HTM, namely WH-1, by replacing the central carbon atom of Spiro-OMeTAD with cyclohexane via a simple and efficient two-step synthetic route. 129 WH-1 had a parallel arrangement structure of two fluorene segments, facilitating the improvement of hole mobility and intermolecular electronic coupling. WH-1 was used as a dopant-free HTM in a mesoporous n–i–p PSC, and a high PCE of 19.5% was obtained, which is the first dispiro-based molecule as a dopant-free HTM for PSCs.…”

Structural Engineering of FDT toward Promising Spiro-Typed Hole-Transporting Materials: Promoting the Hole Transport and Stabilizing the HOMO Levels

“…The suitable energy levels and high hole mobility of HTMs are important prerequisites to acquire the good photoelectric performance of PSCs. Great efforts have been made in recent years to develop the highly efficient HTMs. − Among the various HTMs, organic small molecule HTMs have received widespread attention because of their rich raw materials and easy structural engineering. − …”