A relatively wide-bandgap and air-stable donor polymer for fabrication of efficient semitransparent and tandem organic photovoltaics

Tavakoli, Mohammad Mahdi; Pò, Riccardo; Bianchi, Gabriele; Cominetti, Alessandra; Carbonera, Chiara; Camaioni, Nadia; Tinti, Francesca; Kong, Jing

doi:10.1073/pnas.1907495116

Cited by 24 publications

(23 citation statements)

References 34 publications

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“…In fact, our tandem device is comparable with the state‐of‐art polymers reported in the literature in terms of stability. For instance, in one the stable tandem device reported in the literature, [ 38 ] the device retained 97% of its initial PCE value in ambient condition, which is similar to our stability results. However, we also measured the operational stability of our tandem device under continuous illumination and compared with both single‐junction bottom (PV2000:PCBM) and top (PM6:Y6) cells.…”

Section: Resultssupporting

confidence: 90%

“…Besides reducing the PV losses (in V OC , FF, and current match) in a tandem OSC, the device stability is also required to be considered for the commercialization purposes. [ 7,38 ] Most of the reports in the literature just considered the efficiency of the tandem device, and therefore, more efforts need to be devoted to the stability of OSC tandem devices. Basically, researchers improved the stability of an OSC device by synthesis of donors and acceptors with a stable molecular structure and deep highest occupied molecular orbital level, interface engineering, and using protection and AR layers.…”

Section: Introductionmentioning

confidence: 99%

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Suppression of Photovoltaic Losses in Efficient Tandem Organic Solar Cells (15.2%) with Efficient Transporting Layers and Light Management Approach

Tavakoli

Kong

2020

Energy Tech

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Organic solar cells (OSCs) have been investigated by many researchers due to their outstanding properties, such as flexibility, semi-transparency, lightweight, low-cost processing, and large-area production. [1-7] To improve the efficiency of OSCs, several strategies, such as ternary blend, tandem design, new donors, and non-fullerene acceptors, have been recently developed, [8-14] where, over the past year, the efficiency of OSCs was increased drastically up to 16.5% for a single junction [15] and 17.3% for tandem [16] designs. Among these approaches, tandem OSC has been developed by stacking subcells to improve the absorption of the solar cell in different regions of the solar spectrum. [17,18] To design an efficient tandem device, effective approaches, including photon utilization efficiency, bandgap engineering, and interface engineering, need to be considered to minimize the photovoltaic (PV) losses. [19,20] Finding efficient recombination layers and transporting layers is the most effective way to reduce the losses in the tandem device. [21,22] Organic semiconductors have shorter diffusion length as compared with inorganic ones, which results in the recombination of excitons before separation into the free carriers at the interface of donor and acceptor. [23,24] To address this issue, bulk heterojunction OSCs have been developed by blending the donor and acceptor into the active layer. [25-27] Using this concept, the thickness of the absorber layer in OSCs can be increased to over 100 nm, thus improving light absorption. However, the fill factor (FF) of OSCs is often decreased by increasing the thickness of the active layer. In fact, higher shunt resistance (R SH) and lower series resistance (R S) result in improved FF in a solar cell. In an OSC device, R SH and R S are influenced by variation of recombination in the active layer, where R SH is enhanced by reducing the monomolecular recombination (recombination of a bound geminate holeelectron pair before converting to the mobile carriers), and R S is reduced by an increase in bimolecular recombination (recombination of mobile holes and electrons at acceptor/donor interface). [28,29] In a tandem OSC, the active layers in both subcells are thinner than a normal cell, and thus, the recombination will be reduced, leading to a higher FF. [30] In this regard, Liu et al. [31] reported a tandem OSC with a high FF of 77% and a PCE of 14%, using similar active layers in both subcells and tuning their thicknesses. In fact, fabrication of a tandem device can be a good solution to not only enhance the open circuit voltage and PCE of the OSCs, but also improve the light stability of the top cell OSC (where the active layer has lower bandgap) due to the filtering of high energy photons by the bottom cell. Interface engineering using efficient transporting and recombination layers in a tandem OSC is a great strategy to minimize

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Suppression of Photovoltaic Losses in Efficient Tandem Organic Solar Cells (15.2%) with Efficient Transporting Layers and Light Management Approach

Tavakoli

Kong

2020

Energy Tech

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“…The surface roughness of the perovskite film can induce surface recombination at HTL/perovskite interface, resulting in lower open circuit voltage ( V OC ). [ 44–46 ] The crystallinity of the perovskite films deposited on solution‐ and evaporation‐based PTAA was investigated by X‐ray diffraction (XRD) pattern, as shown in Figure S5, Supporting Information. As seen, the perovskite film on the evaporated PTAA film shows peaks with slightly higher intensity, indicating better quality of the perovskite in this sample.…”

Section: Figurementioning

confidence: 99%

All‐Vacuum‐Processing for Fabrication of Efficient, Large‐Scale, and Flexible Inverted Perovskite Solar Cells

Tavakoli

2020

Physica Rapid Research Ltrs

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Vacuum deposition of transporting layers, especially the hole‐transporting layer (HTL), is still a big challenge for the fabrication of large‐area perovskite solar cells (PSCs). In this work, efficient and large‐area PSCs are fabricated by thermal evaporation of all the layers. Poly(bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine) (PTAA) is used as the HTL, and a compact layer of PTAA with low thickness (2–10 nm) is successfully deposited using thermal evaporation. The optical and ultraviolet photoelectron spectroscopy (UPS) measurements prove that the evaporated PTAA has a great match with the single A‐cation methylammonium triiodide perovskite film in terms of quenching effect and band alignment. After fabrication of the inverted architecture using all‐vacuum‐processing, PSCs with power conversion of efficiencies (PCEs) of 19.4% for small area (0.054 cm2) and 18.1% for large area (1 cm2) are achieved, which are higher than those of solution‐based devices. A flexible PSC with PCE of 17.27% is also fabricated using this approach. Moreover, the fabricated PSCs, using the vacuum technique, show negligible hysteresis and good stability, better than the devices fabricated on spin‐coated PTAA. This work highlights the potential of vacuum deposition for scale‐up and commercialization of PSCs.

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“…28,29 On this respect, the device engineering has played a key role for example with the development of tandem devices, consisting of multiple layers of different materials which usually show complementary absorption, [30][31][32] but the tandem devices fabrication requires complicated and expensive manufacturing. [32][33][34][35][36][37] A promising alternative for combining the improved photoconversion of tandem devices with the simplicity of the typical manufacturing processes of OSCs, is the realization of three-component heterojunctions. In this regard, Honda et al reported an enhancement of the light-harvesting efficiency in P3HT:PCBM BHJ solar cells by employing nearinfrared phthalocyanine molecules as the third component of the active layer.…”

Section: Introductionmentioning

confidence: 99%

Synergies and compromises between charge and energy transfers in three-component organic solar cells

Sartorio

Giuliano

Scopelliti

et al. 2020

Phys. Chem. Chem. Phys.

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A relatively wide-bandgap and air-stable donor polymer for fabrication of efficient semitransparent and tandem organic photovoltaics

Cited by 24 publications

References 34 publications

Suppression of Photovoltaic Losses in Efficient Tandem Organic Solar Cells (15.2%) with Efficient Transporting Layers and Light Management Approach

Suppression of Photovoltaic Losses in Efficient Tandem Organic Solar Cells (15.2%) with Efficient Transporting Layers and Light Management Approach

All‐Vacuum‐Processing for Fabrication of Efficient, Large‐Scale, and Flexible Inverted Perovskite Solar Cells

Synergies and compromises between charge and energy transfers in three-component organic solar cells

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