The role of the third component in ternary organic solar cells

Gasparini, Nicola; Salleo, Alberto; McCulloch, Iain; Baran, Derya

doi:10.1038/s41578-019-0093-4

Cited by 389 publications

(312 citation statements)

References 143 publications

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“…[9][10][11][12][13][14][15][16] Noteworthy improvements have been made over the last few years, and state-of-the-art NFA-OSCs have been reported with PCEs over 16 %, thus outperforming their fullerene-based counterparts. [19,20] Additionally, the reduction in the bandgap of NFAs opens up the possibility to fabricate semitransparent OSCs that could be applied in building-integrated photovoltaics or power generating greenhouses. [19,20] Additionally, the reduction in the bandgap of NFAs opens up the possibility to fabricate semitransparent OSCs that could be applied in building-integrated photovoltaics or power generating greenhouses.…”

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confidence: 99%

“…[17,18] In tandem and ternary systems, PCEs reaching even up to 17.3% have been recently achieved. [19,20] Additionally, the reduction in the bandgap of NFAs opens up the possibility to fabricate semitransparent OSCs that could be applied in building-integrated photovoltaics or power generating greenhouses. [21][22][23][24] To further improve the performance of OSCs, loss-processes such as nongeminate recombination, the recombination of electrons and holes which do not originate from the same exciton, have to be curtailed.…”

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confidence: 99%

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Quantifying the Nongeminate Recombination Dynamics in Nonfullerene Bulk Heterojunction Organic Solar Cells

Vollbrecht

Брус

et al. 2019

Advanced Energy Materials

121

145

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the continued research has led to power conversion efficiencies (PCEs) over 11% for single-junction devices. [7,8] Be that as it may, difficulties in tuning the molecular structure and electronic properties, as well as the comparatively high cost of production of fullerene-based acceptors are drawbacks that have triggered the search for nonfullerene acceptors (NFAs) as an alternative. [9][10][11][12][13][14][15][16] Noteworthy improvements have been made over the last few years, and state-of-the-art NFA-OSCs have been reported with PCEs over 16 %, thus outperforming their fullerene-based counterparts. [17,18] In tandem and ternary systems, PCEs reaching even up to 17.3% have been recently achieved. [19,20] Additionally, the reduction in the bandgap of NFAs opens up the possibility to fabricate semitransparent OSCs that could be applied in building-integrated photovoltaics or power generating greenhouses. [21][22][23][24] To further improve the performance of OSCs, loss-processes such as nongeminate recombination, the recombination of electrons and holes which do not originate from the same exciton, have to be curtailed. This includes bimolecular recombination (also known as Langevin recombination), where charge carriers recombine directly from band to band, as well as trap-assisted recombination (also known as Shockley-Read-Hall recombination), where states deep in the bandgap act as efficient recombination centers. A detailed understanding of these mechanisms responsible for the aforementioned recombination losses is required. [25] Whether or not there are considerable differences in recombination dynamics between NFA-OSCs and fullerene-based OSCs, has yet to be understood since most research in regard to recombination dynamics was performed only with OSCs employing fullerene acceptors. [26][27][28] Furthermore, the majority of studies describe recombination dynamics based on a numerical, drift-diffusion model under the assumption of an effective-medium for the BHJ active layer. [29][30][31][32][33][34][35][36][37][38] The concentration of charge carriers is the key differential parameter in the theory of recombination dynamics. However, only integral parameters (electrical conductivity, impedance, open-circuit voltage, V OC ) can be directly measured by experiments. Therefore, the primary challenge of the theoretical background of any method developed to quantify recombination processes in photovoltaic devices is based on finding the appropriate relationship between the measured In this study, a comprehensive analytical model to quantify the total nongeminate recombination losses, originating from bimolecular as well as bulk and surface trap-assisted recombination mechanisms in nonfullerene-based bulk heterojunction organic solar cells is developed. This proposed model is successfully employed to obtain the different contributions to the recombination current of the investigated solar cells under different illumination intensities. Additionally, the model quantitatively describes the experimentally measured ope...

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confidence: 99%

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confidence: 99%

Quantifying the Nongeminate Recombination Dynamics in Nonfullerene Bulk Heterojunction Organic Solar Cells

Vollbrecht

Брус

et al. 2019

Advanced Energy Materials

121

145

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“…These efforts include new material synthesis, fine tuning the donor:acceptor (D:A) compositions/morphology, and the optimization of fabrication process. [5][6][7][8][9][10][11][12] A key accomplishment of these efforts is the identification of small molecule acceptors (SMAs). In particular, a bulk heterojunction (BHJ) OPV cell using SMAs (e.g., ITIC-based acceptors) can attain simultaneously a low V oc loss and a high efficiency.…”

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confidence: 99%

Enhanced Electron Transport and Heat Transfer Boost Light Stability of Ternary Organic Photovoltaic Cells Incorporating Non‐Fullerene Small Molecule and Polymer Acceptors

Yin

Chiu

et al. 2019

Adv Elect Materials

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fabricating flexible, low-cost, low thermal budget, and lightweight solar panels. [1][2][3][4] Over the past decades, great efforts have been devoted for high-performance OPVs. These efforts include new material synthesis, fine tuning the donor:acceptor (D:A) compositions/morphology, and the optimization of fabrication process. [5][6][7][8][9][10][11][12] A key accomplishment of these efforts is the identification of small molecule acceptors (SMAs). In particular, a bulk heterojunction (BHJ) OPV cell using SMAs (e.g., ITIC-based acceptors) can attain simultaneously a low V oc loss and a high efficiency. With fused-ring electron acceptors (FREAs), the highest power conversion efficiencies (PCEs) for the single junction BHJ and tandem OPV devices have gone beyond 15% and 17%, respectively. [13,14] Besides the efficiency, the processibility and stability are also important attributes of BHJ cells. [15,16] However, at present, there is a general lack of knowledge in understanding the operation stability of the high efficiency SMA-based devices. To date, researchers have noticed the problem of photostability in SMA-based OPV devices. [17] Xiao et al. compared a series of PTB7-Th-based solar cells with different acceptors, and the results indicate that the poor miscibility between the donor polymers and SMAs is the primary cause of the morphology degradation, suppressed Operation stability remains the key hurdle for the best-performing nonfullerene small molecule acceptor (SMA)-based organic photovoltaic (OPV) devices. Among all SMAs, the ITIC-derivative is the most promising OPV cell using ITIC-derivative acceptors with a power conversion efficiency > 15%. However, the operation stability of SMA-based devices under illumination is relatively inferior when compared to bulk-heterojunction (BHJ) cells that employ polymeric acceptors. Here, a polymer acceptor N2200 is used as the ternary component to study the device performance of ITIC-derivative-based PBDB-T:ITIC-M and PBDB-T-2F:IT-4F BHJ solar cells, which currently are the representative state-of-the-art high-performance OPV devices. The ternary solar cells with low N2200 loading enjoy significantly improved operation stability, while maintaining a high power conversion efficiency. A comprehensive mechanism study is conducted on the ternary OPV systems in i) electronic and ii) thermal aspects. For i), the ternary BHJs show remarkably improved electron transport. For ii), the thermal diffusivity D of the ternary BHJ exhibits almost an order of magnitude improvement in D values, indicating that heat can be more effectively transferred out of such films than binary counterpart. The results show that N2200 ternary loading facilitates an improved network for both electron transport and heat dissipation, leading to improved photostability.

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“…Meanwhile, the conductivity and transmittance of the intermediate electrode should be simultaneously optimized by altering the thickness of the intermediate electrode to prepare highly efficient tandem OPVs . Ternary strategy can provide a simple method to recombine advantages of three materials into one OPV, which has been commonly demonstrated from different systems with two donors or two acceptors . In fact, many issues are needed to be deeply investigated to guide material selection for achieving efficient ternary OPVs.…”

Section: The Photovoltaic Parameters Of Opvsmentioning

confidence: 99%

“…[19][20][21] Ternary strategy can provide a simple method to recombine advantages of three materials into one OPV, which has been commonly demonstrated from different systems with two donors or two acceptors. [22][23][24][25][26][27][28] In fact, many issues are needed to be deeply investigated to guide material selection for achieving efficient ternary OPVs. Meanwhile, the underlying reasons of performance improvement should be further clarified to promote the field development.…”

mentioning

confidence: 99%

Inverted Ternary Organic Photovoltaics with Alloyed Acceptor Exhibiting 12.29% Efficiency

Bao

Wang

Zhang

et al. 2019

Physica Rapid Research Ltrs

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A series of inverted organic photovoltaics (OPVs) are fabricated with PBDB‐T as donor and nonfullerene materials (ITCC and IT‐M) as acceptors, respectively. Power conversion efficiencies (PCEs) of IT‐M‐ and ITCC‐based OPVs are 11.20% and 8.70%, respectively. A 12.29% PCE is achieved from the optimized ternary OPVs with active layers containing 20 wt% ITCC in acceptors, resulting from the simultaneous improvement of the fill factor (FF) of 74.31%, short‐circuit current density (JSC) of 17.41 mA cm−2, as well as open‐circuit voltage (VOC) of 0.952 V. Over 9% PCE improvement is obtained by using the ternary strategy, which is attributed to the complementary absorption spectra, excellent compatibility, as well as well‐matched energy levels of used materials. This work indicates the ternary strategy as an efficient method to achieve efficient OPVs while keeping the simplicity of the fabrication process.

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The role of the third component in ternary organic solar cells

Cited by 389 publications

References 143 publications

Quantifying the Nongeminate Recombination Dynamics in Nonfullerene Bulk Heterojunction Organic Solar Cells

Quantifying the Nongeminate Recombination Dynamics in Nonfullerene Bulk Heterojunction Organic Solar Cells

Enhanced Electron Transport and Heat Transfer Boost Light Stability of Ternary Organic Photovoltaic Cells Incorporating Non‐Fullerene Small Molecule and Polymer Acceptors

Inverted Ternary Organic Photovoltaics with Alloyed Acceptor Exhibiting 12.29% Efficiency

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