Porphyrin-based thick-film bulk-heterojunction solar cells for indoor light harvesting

Yin, Hang; Chen, Song; Cheung, Sin Hang; Li, Ho Wa; Xie, Yue‐Min; Tsang, Sai‐Wing; Zhu, Xunjin; So, Shu Kong

doi:10.1039/c8tc02838a

Cited by 70 publications

(37 citation statements)

References 41 publications

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“…The carrier mobilities were derived from the dark current density–voltage curves by fitting the J – V curves with the space‐charge‐limited current (SCLC) model (Figure e). Electron‐only devices were fabricated with the structure of ITO/Al/active layer/LiF/Al.…”

Section: Resultsmentioning

confidence: 99%

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

et al. 2020

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Fluorination has proven effective in increasing the absorption, downshifting the energy levels, and enhancing the crystallinity of high‐performance fused‐ring electron acceptors (FREAs). However, an in‐depth understanding of the effects of fluorination is still lacking, as research efforts have mainly focused on increasing the power conversion efficiency (PCE). In addition, fluorination on FREAs has rarely been reported in all‐small‐molecule organic solar cells (ASM OSCs). Herein, fluorination on FREAs is systematically studied in ASM OSCs using the popular FREA 2,2′‐((2Z,2′Z)‐((4,4,9,9‐tetrahexyl‐4,9‐dihydro‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene‐2,7‐diyl)bis(methanylylidene))bis(3‐oxo‐2,3‐dihydro‐1H‐indene‐2,1‐diylidene))dimalononitrile and its fluorinated analog paired with DRCN5T, an oligothiophene donor seldom investigated in ASM OSCs to date. (Photo)physical studies are conducted on both systems and it is identified that, along with the aforementioned ones, fluorination exerts several additional effects, including the following. First, it optimizes the morphology, thereby accelerating charge separation and reducing geminate recombination charge pairs; second, it suppresses energetic disorder; and third, it prolongs the carrier lifetime and thus aids charge extraction. Consequently, the short‐circuit current density and fill factor are significantly enhanced, and in turn, the PCE yields a 36% improvement, climbing to 9.25% and rivaling that of the current state‐of‐the‐art oligothiophene‐donor/nonfullerene ASM OSCs. The insights decipher the working mechanism of ASM OSCs that use fluorinated FREAs, paving the way toward high‐performance ASM OSCs.

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Section: Resultsmentioning

confidence: 99%

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

et al. 2020

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“…Temperature‐dependent electron transport measurements were performed to evaluate the electron energetic disorders σ e and the high temperature limit mobilities μ ∞ of PBDB‐T‐based BHJ films. The Gaussian disorder model (GDM) is used to analyze the temperature‐dependent electron mobilities, that is,

μ_{0} = μ_{\infty} exp ([], - {(\frac{2 σ}{3 k T})}^{2}) exp (β \sqrt{F})

where k is the Boltzmann constant, and μ ∞ is the y ‐intercept from the plot of μ 0 against 1/ T 2 . Figure b plots μ 0, e of PBDB‐T‐based BHJs with various N2200 weight contents as a function of the temperature.…”

Section: Electron Transport Of the Binary And Ternary Bhj Filmsmentioning

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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“…In this spectral region, diffuse ambient light provides universally available energy, which remains otherwise unused. [7][8][9][10][11][12][13][14] Photovoltaic technologies based on amorphous silicon (a-Si), [15][16][17] organic photovoltaics (OPV), 9,18,19 and dye sensitized cells (DSC) [20][21][22] have shown sufficient energy conversion in this region.…”

Section: Introductionmentioning

confidence: 99%

Dye-sensitized solar cells under ambient light powering machine learning: towards autonomous smart sensors for the internet of things

et al. 2020

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Porphyrin-based thick-film bulk-heterojunction solar cells for indoor light harvesting

Abstract: A thick-film (∼200 nm) porphyrin-based P1:PC71BM BHJ solar cell achieves an optimized PCE of 18.2%, under a 300 lux illumination of a 3000 K LED tube.

Cited by 70 publications

References 41 publications

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

Deciphering the Role of Fluorination: Morphological Manipulation Prompts Charge Separation and Reduces Carrier Recombination in All‐Small‐Molecule Photovoltaics

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

Dye-sensitized solar cells under ambient light powering machine learning: towards autonomous smart sensors for the internet of things

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