Constructing Efficient Hole-Transporting Materials by Tuning Fluorine Substitution for Inverted Perovskite Solar Cells with Efficiency Exceeding 20%

Abstract

Three pyrrolo­[3,2-b]­pyrrole (PP) core building block-based dopant-free hole-transporting materials (HTMs) with different fluorine substitutions are synthesized and applied in inverted perovskite solar cells (PSCs). The number and the position of fluorine substitutions display a significant effect on the photochemical and photovoltaic performances of the resulting HTMs. The hexafluorine-substituted HTM 6FPPY shows excellent hole extraction efficiency and achieves a prominent power conversion efficiency (PCE) of 20.1% with negligible hysteresis and good long-term stability. This work provides an avenue for the design of low-cost, dopant-free HTMs for high-performance inverted PSCs.

Recent progress in perovskite solar cells: material science

“…F atom, Xu et al [254] and Cheng et al [255] decorated the core units with multi-F-modified benzene rings, and the resulting HTMs noted as HTMF and 6FPPY exhibited a much stronger interaction with and defect-passivation effect on the perovskite films, offering the devices with PCEs of over 20% and remarkable stability.…”

Interfacial and Molecular Engineering of a Helicene-Based Molecular Semiconductor for Stable and Efficient Perovskite Solar Cells

“…Apart from construction of helicene-based π-linkers, suitable modifications of fluorine on acceptor and lateral-chain groups are also used to improve the performance of HTMs and to restrict the surface defects of perovskite. − Particularly, two isomeric fluorinated analogs of Spiro-OMeTAD (Spiro- m F and Spiro- o F) were designed by Jeong et al through structural engineering . The fabricated PSCs exhibit a high efficiency of 24.8% and long-term stability, indicating that the fluorination of HTMs is an effective method to construct high-efficiency HTMs .…”

Insight into Controlled Surface Passivation of PEDOT:PSS for Defect Density Modulation and Efficient Charge Transport for Perovskite Solar Cells

“…In recent years, single-junction lead halide perovskite solar cells (PSCs) − have shown rapid improvement in their power conversion efficiency (PCE), − exceeding values of 25% . PSCs have become the most discussed photovoltaic technology during these years, attracting huge attention due to their various applications, low cost, and high performance in next-generation photovoltaics. − The unique optical, electronic, and physical properties of lead halide perovskites and optimization in device architecture with suitable stoichiometry and choice of appropriate materials for the hole transport layer (HTL) − and an electron transport layer (ETL) , are the main aspects for the rapid growth of PSCs.…”