Optimizing binding energy and electron-hole pair binding distance for efficient organic solar cells with low voltage loss

Huang, Tingyao; Bai, Yiming; Wang, Jun; Wang, Fuzhi; Dai, Meilin; Han, Fei; Du, S. X.

doi:10.1016/j.solener.2021.10.002

Cited by 7 publications

(1 citation statement)

References 34 publications

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“…Nowadays, DIO and 1-CN, though originated from fullerenebased systems, are also widely applied in high-efficiency nonfullerene-based OSCs. [70][71][72][73][74] Recently, Lu et al studied the phase evolution and vertical morphology of two representative high-efficiency nonfullerene-based OSCs (PBDB-T:ITIC treated with DIO and PM6:Y6 treated with 1-CN, Fig. 2).…”

Section: Nonvolatile Solvent Additivesmentioning

confidence: 99%

Additive-assisted strategy for high-efficiency organic solar cells

Xie,

He,

Zhao

2024

J. Mater. Chem. C

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Section: Nonvolatile Solvent Additivesmentioning

confidence: 99%

Additive-assisted strategy for high-efficiency organic solar cells

Xie,

He,

Zhao

2024

J. Mater. Chem. C

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A Dibenzo[g,p]chrysene‐Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation

Mori,

Jinnai,

Hosoda

et al. 2024

Angewandte Chemie

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Exciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free‐charge carriers, and is known to be an important parameter in determining the performance of organic opto‐electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star‐shaped π‐conjugated compounds DBC‐RD and TPE‐RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC‐RD and TPE‐RD, indicating that these molecules possess similar properties on a single‐molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC‐RD had a smaller Eb value of 0.24 eV compared with that of TPE‐RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC‐RD in pristine film is induced by molecular aggregation. By comparison with TPE‐RD, DBC‐RD showed superior performances in single‐component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films.

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Nonfullerene Acceptors Bearing Spiro‐Substituted Bithiophene Units in Organic Solar Cells: Tuning the Frontier Molecular Orbital Distribution to Reduce Exciton Binding Energy

Wang,

Jinnai,

Urakami

et al. 2024

Angewandte Chemie

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The development of nonfullerene acceptors (NFAs), represented by ITIC, has contributed to improving the power conversion efficiency (PCE) of organic solar cells (OSCs). Although tuning the electronic structures to reduce the exciton binding energy (Eb) is considered to promote photocharge generation, a rational molecular design for NFAs has not been established. In this study, we designed and developed two ITIC‐based NFAs bearing spiro‐substituted bithiophene or biphenyl units (named SpiroT‐DCI and SpiroF‐DCI) to tune the frontier molecular orbital (FMO) distribution of NFAs. While the highest occupied molecular orbitals (HOMOs) of SpiroF‐DCI and ITIC are delocalized in the main π‐conjugated framework, the HOMO of SpiroT‐DCI is distributed on the bithiophene unit. Reflecting this difference, SpiroT‐DCI exhibits a smaller Eb than either SpiroF‐DCI or ITIC, and exhibits greater external quantum efficiency in single‐component OSCs. Furthermore, SpiroT‐DCI shows improved PCEs for bulk‐heterojunction OSCs with a donor of PBDB‐T, compared with that of either SpiroT‐DCI or ITIC. Time‐resolved spectroscopy measurements show that the photo‐induced intermolecular charge separation is effective even in pristine SpiroT‐DCI films. This study highlights the introduction of spiro‐substituted bithiophene units that are effective in tuning the FMOs of ITIC, which is desirable for reducing the Eb and improving the PCE in OSCs.

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Optimizing binding energy and electron-hole pair binding distance for efficient organic solar cells with low voltage loss

Cited by 7 publications

References 34 publications

Additive-assisted strategy for high-efficiency organic solar cells

Additive-assisted strategy for high-efficiency organic solar cells

A Dibenzo[g,p]chrysene‐Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation

Nonfullerene Acceptors Bearing Spiro‐Substituted Bithiophene Units in Organic Solar Cells: Tuning the Frontier Molecular Orbital Distribution to Reduce Exciton Binding Energy

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