An Oxa[5]helicene-Based Racemic Semiconducting Glassy Film for Photothermally Stable Perovskite Solar Cells

Abstract

Summary Attaining the durability of high-efficiency perovskite solar cells (PSCs) operated under concomitant light and thermal stresses is still a serious concern before large-scale application. It is crucial to maintain the phase stability of the organic hole-transporting layer for thermostable PSCs across a range of temperatures sampled during device operation. To address this issue, we propose a racemic semiconducting glassy film with remarkable morphological stability, exemplified here by a low-molecular symmetry oxa[5]helicene-centered organic semiconductor (O5H-OMeDPA). The helical configuration of O5H-OMeDPA confers the trait of multiple-dimension charge transfer to the solid, resulting in high hole mobility of 6.7 × 10 −4 cm 2 V −1 s −1 of a solution-processed glassy film. O5H-OMeDPA is combined with a triple-cation dual-halide lead perovskite to fabricate PSCs with power conversion efficiencies of 21.03%, outperforming the control cells with spiro-OMeTAD (20.44%). Moreover, the cells using O5H-OMeDPA exhibit good long-term stability during full-sunlight soaking at 60°C.

Intrinsic Dynamic and Static Nature of π···π Interactions in Fused Benzene-Type Helicenes and Dimers, Elucidated with QTAIM Dual Functional Analysis

“…Helicenes are chiral; as a result, they are expected to have specific functionalities. Recently, helicenes have been widely applied in various fields [ 1 , 2 , 3 , 4 , 5 ], such as organic semiconductors [ 6 , 7 , 8 , 9 , 10 ], asymmetric catalysis [ 11 , 12 , 13 , 14 , 15 , 16 ], and molecular recognition [ 17 , 18 , 19 , 20 , 21 , 22 ], due to their diverse functionalities in materials. Many studies have also been reported on self-assembly phenomena at metal surfaces [ 23 , 24 , 25 , 26 ] caused by interactions with the π-orbitals of helicenes.…”

Engineering bandgap of CsPbI3 over 1.7 eV with enhanced stability and transport properties

“…Several strategies have been extensively developed to improve the phase stability of CsPbI 3 including composition engineering ( Tian et al., 2020 ; Lau et al., 2019 ; Lu et al., 2020 ), crystallization regulation by introducing Lewis acid-base adducts ( Li et al., 2020a ; Nenon et al., 2018 ) or polymers ( Li et al., 2018a ; Jeong et al., 2020 ; Chen et al., 2019 ) into the CsPbI 3 precursor, surface capping treatments ( Wu et al., 2019 ; Wang et al., 2018 ), and dimension reduction by scaling down to quantum dots ( Bai et al., 2019 ; Sadeghi et al., 2020 ), nanocrystals ( Ghosh et al., 2018 ), or quasi two-dimensional (2D) films ( Qing et al., 2019 ; Zhang et al., 2017 ; Mauck and Tisdale, 2019 ; Liu et al., 2018 ). Among them, composition engineering by partly replacing Cs + with large organic cations can regulate the structural tolerance factor to improve the intrinsic phase stability of CsPbI 3 ( Xu et al., 2017 , 2019 ; Lee et al., 2021 ). The soft lattice of CsPbI 3 induced by its ionic bonding is favorable for a facile cation exchange to regulate the perovskite composition ( Deng et al., 2019 ).…”

D–π–D molecular semiconductors for perovskite solar cells: the superior role of helical versus planar π-linkers

“…32 Recently we reported a racemic glassy lm composed of bis(4-methoxyphenyl)amine functionalized oxa [5] helicene (O5H-OMeDPA) as a donor-p-donor (D-p-D) type HTL for efficient PSCs. 33 Meanwhile, we are also curious to know whether a helicene based organic semiconductor is really superior to its planar counterpart. However the preparation of the perylo [1,12-bcd]furan (PEF) counterpart seems infeasible due to the lack of mature synthetic conditions for PEF.…”