Enantiomerically Pure Fullerenes as a Means to Enhance the Performance of Perovskite Solar Cells

Abstract

The rapidly advancing improvements in perovskite solar cells (PSCs) are driven, in part, by the inclusion of suitable electron transport layers (ETLs) in high performance devices. Fullerene derivatives are particularly useful ETLs in PSCs, but many of the utilized fullerenes are present as isomeric mixtures. The opportunities presented by single‐isomer, single‐enantiomer fullerenes in PSCs are poorly understood. Here, inverted PSCs are prepared using bis[60]phenyl‐C61‐butyric acid methyl ester derivative (anti)16,17‐bis[60]PCBM, comparing the performance of enantiomerically pure material to the corresponding racemate. The single enantiomer devices are found to have an improved performance, giving a power conversion efficiency (PCE) of 23.2%, compared to 20.1% PCE for the racemate. It is also shown that enantiomerically pure PSC modules can be prepared with a state‐of‐the‐art PCE of 20.1%. Such excellent performance for the single enantiomer devices is accompanied by enhanced operational stability. This study thus provides strong evidence that single isomer ETLs can provide important improvements in PSC performance and it positions chiral fullerenes as an exciting material class moving forward.

Recent advances in supramolecular fullerene chemistry

“…Recent work by diverse groups in materials science established that significantly higher device efficiencies can be obtained when using isomerically pure fullerenes rather than mixtures of regioisomers, diastereomers or racemates. 23,[35][36][37] The classic approach to address the regioisomer problem in C 60 bis-addition is the use of a tether. Pioneered by Diederich, this method has the disadvantage that the tether remains attached to the fullerene, thus restricting the scope of products, unless degradable linkers are used, such as the dialkoxysilanes recently employed by Nierengarten.…”

“…Because most fullerene multi-adducts are chiral, achieving enantioselectivity is a formidable challenge whose importance has been underscored by recent work by Fuchter demonstrating that homochiral fullerenes outperform the corresponding racemates as electron transport layers in perovskite solar cells. 37 While this challenge has been approached previously using chiral reagents/catalysts, 55 one recent report by Nitschke and coworkers demonstrated the first supramolecular approach enabling the enantioselective functionalization of fullerenes ( Fig. 6 ).…”

Recent Advances of Inverted Perovskite Solar Cells

“…A higher PCE of 23.2% based on PFBS-C12 compared to PCBM-based devices could be achieved . Besides, PBDTTT-C-T-doped PCBM and enantiomerically pure PCBM were also introduced to improve the conductivity of PCBM to improve the electronic extraction ability of PCBM and enhance the PCE of inverted PSCs. , ICBA as another C 60 derivative can be used to match with the low CBM of Sn-based perovskite because of its lower LUMO than PCBM or C 60 . The V OC of the corresponding device was enhanced from 0.6 to 0.94 V .…”

Numerical Analysis of Stable (FAPbI3)0.85(MAPbBr3)0.15-Based Perovskite Solar Cell with TiO2/ZnO Double Electron Layer

“…Solar cells, which convert ecologically friendly and inexhaustible solar energy into electrical power, are expected to meet all the global energy demand [2]. Perovskite solar cells (PSCs) are one of the most promising technologies for next generation photovoltaics [3] due to their many superior optical and electronic properties, such as their low costs, simple manufacturing, excellent optical absorption, high carrier mobilities, and large diffusion lengths [4,5]. Moreover, the solution-based preparation of perovskite thin films is rather cost-effective as it only requires low temperatures and small amounts of materials [6].…”