Design and application of volatilizable solid additives in non-fullerene organic solar cells

Yu, Runnan; Yao, Huifeng; Lei, Hong; Qin, Yunpeng; Zhu, Jie; Cui, Yong; Li, Sunsun; Hou, Jianhui

doi:10.1038/s41467-018-07017-z

Cited by 224 publications

(195 citation statements)

References 38 publications

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“…The doped cells retain their superior stability even after 1000 h of storage with the measured PCE reducing by only ≈23% as compared to pristine (w/o) devices (≈50%). Since in both types of cells, the BHJ‐electrode(s) interface(s) remain the same, any differences in the PCE degradation are most likely ascribed to changes in the microstructure of the BHJ layer 45. Although being preliminary, the results indicate the potential of BV‐doping for stabilizing the microstructure of the BHJ.…”

Section: Summary Of Operating Parameters Of Solar Cells Based On Pm6:mentioning

confidence: 99%

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

et al. 2020

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Molecular doping is often used in organic semiconductors to tune their (opto)electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p‐type dopants. In an effort to control the charge transport within the bulk‐heterojunction (BHJ) of OPVs, the n‐type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small‐molecule acceptor IT‐4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n‐type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge‐carrier density within the BHJ, while significantly extending the cells' shelf‐lifetime. The n‐type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n‐doping strategy highlights electron transport in NFA‐based OPVs as being a key issue.

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Section: Summary Of Operating Parameters Of Solar Cells Based On Pm6:mentioning

confidence: 99%

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

et al. 2020

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“…The optimal morphology in BHJ devices is usually a metastable state and will further move toward a thermodynamic equilibrium state to form phase separation, leading to deterioration of lifetime and performance of OSCs. Based on this view, a lot of methods are carried out to control the morphology and to further enhance the performance of OSCs . However, these approaches are generally limited to the specific materials and photovoltaic systems; therefore, it is necessary to develop a more universal and facile fabrication process to solve above problems and as well as to improve the stature of OSCs.…”

Section: Detailed Photovoltaic Parameters Of Blade‐coated Oscs Under mentioning

confidence: 99%

Sequential Blade‐Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

Wang

Zhu

Naveed

et al. 2020

Advanced Energy Materials

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As a predominant fabrication method of organic solar cells (OSCs), casting of a bulk heterojunction (BHJ) structure presents overwhelming advantages for achieving higher power conversion efficiency (PCE). However, long‐term stability and mechanical strength are significantly crucial to realize large‐area and flexible devices. Here, controlling blend film morphology is considered as an effective way toward co‐optimizing device performance, stability, and mechanical properties. A PCE of 12.27% for a P‐i‐N‐structured OSC processed by sequential blade casting (SBC) is reported. The device not only outperforms the as‐cast BHJ devices (11.01%), but also shows impressive stability and mechanical properties. The authors corroborate such enhancements with improved vertical phase separation and purer phases toward more efficient transport and collection of charges. Moreover, adaptation of SBC strategy here will result in thermodynamically favorable nanostructures toward more stable film morphology, and thus improving the stability and mechanical properties of the devices. Such co‐optimization of OSCs will pave ways toward realizing the highly efficient, large‐area, flexible devices for future endeavors.

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“…Therefore, the π–π stacking of end‐groups between two adjacent molecules offers the main intermolecular charge transport channels . By utilizing the intrinsic structural features of A–D–A acceptors, we have designed and applied volatilizable solid additives to improve the efficiency and stability of the fullerene‐free PSCs . We have preliminarily proved that the volatilizable solid additives combined with thermal annealing are beneficial for the π–π interaction of acceptors, resulting in enhanced photovoltaic performances of the PSCs.…”

Section: Photovoltaic Parameters For Pbdb‐tcl:it‐4f Based Devices Promentioning

confidence: 99%

Enhanced π–π Interactions of Nonfullerene Acceptors by Volatilizable Solid Additives in Efficient Polymer Solar Cells

et al. 2019

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Fine‐tuning of the nanoscale morphologies of the active layers in polymer solar cells (PSCs) through various techniques plays a vital role in improving the photovoltaic performance. However, for emerging nonfullerene (NF) PSCs, the morphology optimization of the active‐layer films empirically follows the methods originally developed in fullerene‐based blends and lacks systematic studies. In this work, two solid additives with different volatilities, SA‐4 and SA‐7, are applied to investigate their influence on the morphologies and photovoltaic performances of NF‐PSCs. Although both solid additives effectively promote the molecular packing of the NF acceptors, due to the higher volatility of SA‐4, the devices processed with SA‐4 exhibit a power conversion efficiency of 13.5%, higher than that of the control devices, and the devices processed with SA‐7 exhibit poor performances. Through a series of detailed morphological analyses, it is found that the volatilization of SA‐4 after thermal annealing is beneficial for the self‐assembly packing of acceptors, while the residuals due to the incomplete volatilization of SA‐7 have a negative effect on the film morphology. The results delineate the feasibility of applying volatilizable solid additives and provide deeper insights into the working mechanism, establishing guidelines for further material design of solid additives.

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Design and application of volatilizable solid additives in non-fullerene organic solar cells

Cited by 224 publications

References 38 publications

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

Sequential Blade‐Coated Acceptor and Donor Enables Simultaneous Enhancement of Efficiency, Stability, and Mechanical Properties for Organic Solar Cells

Enhanced π–π Interactions of Nonfullerene Acceptors by Volatilizable Solid Additives in Efficient Polymer Solar Cells

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