Donor polymer design enables efficient non-fullerene organic solar cells

Li, Zhengke; Jiang, Kui; Yang, Guofang; Lai, Joshua Yuk Lin; Ma, Tingxuan; Zhao, Jingbo; Ma, Wei; Yan, He

doi:10.1038/ncomms13094

Cited by 352 publications

(276 citation statements)

References 59 publications

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“…Ternary OSCs were fabricated in a configuration of tin-doped indium oxide (ITO)/ZnO/PTFB-O:SMA1:SMA2/ V 2 O 5 /Al (Figure 1c), where SMA1 and SMA2 are the two small molecular acceptors. [67] The weight ratio is kept at 1:1.5 (polymer:total acceptor) for all ternary blends with only the SMAs' relative weight ratio being tuned. [67] The weight ratio is kept at 1:1.5 (polymer:total acceptor) for all ternary blends with only the SMAs' relative weight ratio being tuned.…”

Section: Ternary Blend Design and Photovoltaic Device Performancementioning

confidence: 99%

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

Jiang

Zhang

Yang

et al. 2017

Advanced Energy Materials

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148

114

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of multijunction architecture increases the absorption breadth of a solar cell device, the difficulty of device fabrication and therefore the cost for large-scale production are significantly raised. To maintain the simplicity of the single junction structure and in the meantime broaden the absorption range of the solar cell, ternary OSCs have been developed where two donors and one acceptor or one donor and two acceptors are blended together to form the active layer. Important advances have been realized for ternary OSCs with best PCEs reaching beyond 10%. [11,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] However, one main constraint that slows down the development of ternary OSC is the difficulty in controlling the morphology of ternary blends. It is commonly accepted that the bulk-heterojunction (BHJ) morphology for a two-component system is already complex. [25,[30][31][32][33][34] A threephase model has been generally utilized to describe the complicated morphology where a relatively pure donor phase, a relatively pure acceptor phase, and a intermixed donor:acceptor phase coexist in the active medium. [35][36][37][38][39][40][41][42] Apparently, the morphology formed by ternary blends would be even more challenging to evaluate. Due to the absence of effective methods to control the morphology, most of the previous reports on ternary OSCs only focused on one single material combination, Ternary organic solar cells (OSCs) have attracted much research attention, as they can maintain the simplicity of the single-junction device architecture while broadening the absorption range of OSCs. However, one main challenge that limits the development of ternary OSCs is the difficulty in controlling the morphology of ternary OSCs. In this paper, an effective approach to control the morphology is presented that leads to multiple cases of efficient nonfullerene ternary OSCs with efficiencies of up to 11.2%. This approach is based on a donor polymer with strong temperature dependent aggregation properties processed from hot solutions without any solvent additives and a pair of small molecular acceptors (SMAs) that have similar surface tensions and thus low propensity to form discrete phases. Such a ternary blend exhibits a simplified bulk-heterojunction morphology that is similar to the morphology of previously reported binary blends. As a result, an almost linear relationship between V OC and film composition is observed for all nonfullerene ternary devices. Meanwhile, by carefully designing a control system with a large interfacial tension, a different phase separation and V OC dependence is demonstrated. This morphology control approach can be applicable to more material systems and accelerates the development of the ternary OSC field.

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Section: Ternary Blend Design and Photovoltaic Device Performancementioning

confidence: 99%

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

Jiang

Zhang

Yang

et al. 2017

Advanced Energy Materials

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148

114

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“…[19] Taking PTFB-O and PTFB-P with nearly identical chemical structures, energy levels, and absorption spectrum, for example, PTFB-P is significantly more crystallinity than PTFB-O due to the C2 symmetry of the difluorinated monomer unit. Previous studies indicate that polymers with slightly reduced crystallinity maybe a better match for nonfullerene acceptor.…”

Section: Charge Mobilities Domain Purity and Domain Spacingmentioning

confidence: 99%

Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells

Jiang

Chow

et al. 2017

Advanced Energy Materials

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Nonfullerene polymer solar cells (PSCs) based on polymer donors and nonfullerene small molecular acceptors (SMAs) have recently attracted considerable attention. Although much of the progress is driven by the development of novel SMAs, the donor polymer also plays an important role in achieving efficient nonfullerene PSCs. However, it is far from clear how the polymer donor choice influences the morphology and performance of the SMAs and the nonfullerene blends. In addition, it is challenging to carry out quantitative analysis of the morphology of polymer:SMA blends, due to the low material contrast and overlapping scattering features of the π–π stacking between the two organic components. Here, a series of nonfullerene blends is studied based on ITIC‐Th blended with five different donor polymers. Through quantitative morphology analysis, the (010) coherence length of the SMA is characterized and a positive correlation between the coherence length of the SMA and the device fill factor (FF) is established. The study reveals that the donor polymer can significantly change the molecular ordering of the SMA and thus improve the electron mobility and domain purity of the blend, which has an overall positive effect that leads to the enhanced device FF for nonfullerene PSCs.

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“…An optimized PCE of 9.6% with high FF of 0.671 was attained with wide bandgap polymer PDBT‐T1. Moreover, with medium bandgap polymer PTFB‐O, improved PCE of 10.88% with J SC of 17.6 mA cm −2 and FF of 0.69 was reported for ITIC‐Th ‐based OSC due to smaller pure domain reducing charge recombination …”

Section: Nfas and Various Aspects Of Freasmentioning

confidence: 98%

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

Dey

2019

Small

139

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The quest for sustainable energy sources has led to accelerated growth in research of organic solar cells (OSCs). A solution‐processed bulk‐heterojunction (BHJ) OSC generally contains a donor and expensive fullerene acceptors (FAs). The last 20 years have been devoted by the OSC community to developing donor materials, specifically low bandgap polymers, to complement FAs in BHJs. The current improvement from ≈2.5% in 2013 to 17.3% in 2018 in OSC performance is primarily credited to novel nonfullerene acceptors (NFA), especially fused ring electron acceptors (FREAs). FREAs offer unique advantages over FAs, like broad absorption of solar radiation, and they can be extensively chemically manipulated to tune optoelectronic and morphological properties. Herein, the current status in FREA‐based OSCs is summarized, such as design strategies for both wide and narrow bandgap FREAs for BHJ, all‐small‐molecule OSCs, semi‐transparent OSC, ternary, and tandem solar cells. The photovoltaics parameters for FREAs are summarized and discussed. The focus is on the various FREA structures and their role in optical and morphological tuning. Besides, the advantages and drawbacks of both FAs and NFAs are discussed. Finally, an outlook in the field of FREA‐OSCs for future material design and challenges ahead is provided.

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Donor polymer design enables efficient non-fullerene organic solar cells

Cited by 352 publications

References 59 publications

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

Multiple Cases of Efficient Nonfullerene Ternary Organic Solar Cells Enabled by an Effective Morphology Control Method

Influence of Donor Polymer on the Molecular Ordering of Small Molecular Acceptors in Nonfullerene Polymer Solar Cells

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

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