Thick-film Organic Solar Cells Research Articles

Efficient organic solar cells enabled by sustainable and synergetic device engineering

In order to accelerate the transfer of organic solar cells (OSCs) from lab to fab, this work develops a synergetic strategy by integrating low-cost material, green solvent, bio-based additive and low-temperature post-treatment to sustainably fabricate OSCs. The donor polymer PTQ10 composing of simple building blocks, accompanied by the acceptor L8-BO, is dissolved in the green solvent tetrahydrofuran, wherein a bio-based cinnamonitrile is firstly used as solvent additive. Moreover, fluorous solvent soaking (FSS) is employed as post-treatment to replace the high-temperature and time-consuming thermal annealing. Systematic investigations are performed to unravel the mechanism of the device engineering developed in this work. Differing from the one-way movement of additive, the fluorous solvent can penetrate into and come out the film in cycles. Meanwhile, some L8-BO is selectively dissolved and brought out by the fluorous solvent, so this partial L8-BO bears the function as solid additive to optimize the morphology. As a result, the device achieves a remarkable power conversion efficiency of 17.11%, among the best efficiencies of OSCs prepared by non-halogenated non-aromatic solvents. In addition, the excellent universality ensures this strategy is also effective in the thick-film OSCs.

Synergetic Strategy for Highly Efficient and Super Flexible Thick‐film Organic Solar Cells (Adv. Energy Mater. 31/2022)

Organic Photovoltaics In article number 2201614, Shuguang Wen, Chunming Yang, Xichang Bao, and co-workers report a synergistic strategy to fabricate efficient and super flexible thick-film organic solar cells (OSCs). The proposed comprehensive regulation of intra- and inter-domain interactions in the active layer points to an important research direction for the thickness sensitivity and mechanical stability issues facing flexible OSC applications.

Process-Aid Solid Engineering Triggers Delicately Modulation of Y-Series Non-Fullerene Acceptor for Efficient Organic Solar Cells.

Volatile solids with symmetricπ-backbone are intensively implemented on manipulating the nanomorphology for improving the operability and stability of organic solar cells. However, due to the isotropic stacking, the announced solids with symmetric geometry cannot modify the microscopic phase separation and component distribution collaboratively, which will constrain the promotion of exciton splitting and charge collection efficiency. Inspired by the superiorities of asymmetric configuration, a novel process-aid solid (PAS) engineering is proposed. By coupling with BTP core unit in Y-series molecule, an asymmetric, volatile 1,3-dibromo-5-chlorobenzene solid can induce the anisotropic dipole direction, elevated dipole moment, and interlaminar interaction spontaneously. Due to the synergetic effects on the favorable phase separation and desired component distribution, the PAS-treated devices feature the evident improvement of exciton splitting, charge transport, and collection, accompanied by the suppressed trap-assisted recombination. Consequently, an impressive fill factor of 80.2% with maximum power conversion efficiency (PCE) of 18.5% in the PAS-treated device is achieved. More strikingly, the PAS-treated devices demonstrate a promising thickness-tolerance character, where a record PCE of 17.0% is yielded in PAS devices with a 300nm thickness photoactive layer, which represents the highest PCE for thick-film organic solar cells.

Electron-deficient TVT unit-based D–A polymer donor for high-efficiency thick-film OSCs

As the power conversion efficiencies of organic solar cells (OSCs) have been improved continuously in recent years, more attention will be paid to the industrial production and practical application of OSCs. However, there are still many problems to be solved in the process of large-scale production. Among them, reducing the costs of the materials and enhancing the film-thickness tolerance of the active layer are the two key points. Therefore, it is urgent to develop organic semiconductor materials which are easy to synthesize and suitable for the construction of high-efficiency, thick-film OSCs. In this work, we have focused on the (E)−2-[2-(thiophen-2-yl)vinyl]thiophene (TVT) unit because of its unique coplanar structure. And we noticed that TVT was mostly used as an electron-donating unit in the previous reports. However, we have modified TVT into electron-withdrawing unit by the introduction of fluorine atoms/ester groups. And two new donor–acceptor (D–A) copolymers have been obtained by combining the electron-withdrawing TVT unit with benzo[2,1-b:4,5-b′]dithiophene (BDT) unit. Among them, the polymer based on the ester modified TVT unit presents excellent photovoltaic performance by virtue of its good solubility and preferable molecular stacking mode, and the corresponding devices also show extraordinarily high-thickness tolerance. The emergence of this new electron-withdrawing TVT unit will undoubtedly further promote the development of low-cost, high-efficiency, thick-film OSCs.

Morphology Regulation by Upside-Down Thermal Annealing Based on Blend Thick-Film Organic Solar Cells

Morphology Regulation by Upside-Down Thermal Annealing Based on Blend Thick-Film Organic Solar Cells

Progress and prospects of thick-film organic solar cells

This review summarizes the development of high efficiency thick-film organic solar cells, and presents the prospect of thick-film organic solar cells for commercial applications in the future.

Efficient thick film non-fullerene organic solar cells enabled by using a strong temperature-dependent aggregative wide bandgap polymer

In this work, a temperature-dependent aggregative polymer (PBDT-DTBTO) has been successfully explored to realize efficient thick film organic solar cells (OSCs). PBDT-DTBTO possesses a deep HOMO energy level of −5.35 eV and a wide bandgap of 1.76 eV, which is complementary to the near-infrared absorption of the paired non-fullerene acceptor, INPIC-4F. We reveal the efficacy of the temperature-dependent aggregative PBDT-DTBTO/INPIC-4F bulk-heterojunction (BHJ) blend for thick film OSCs through tuning the processing solvent and thermal annealing temperature. The results show that the device using chlorobenzene as the processing solvent only yields a mediocre power conversion efficiency (PCE) of 8.69%. Whereas, a superior PCE of 13.1% can be achieved by using chloroform (CF) as the processing solvent and proper thermal annealing. The morphological analysis shows that the bicontinuous network of the PBDT-DTBTO/INPIC-4F BHJ blend possesses a preferential face-on orientation when using CF as the processing solvent and thermal annealing, resulting in suppressed charge recombination and superior charge transport in the derived device. Moreover, the PBDT-DTBTO/INPIC-4F-based OSC demonstrates a high thickness toleration of the BHJ layer, which can still deliver a high PCE of 12.6% while the thickness of the BHJ layer is increased to ~320 nm. More encouragingly, a promising PCE of over 12% can also be achieved for the device fabricated by blade-coating, revealing its great potential for the high-throughput solution-coating process.

Over 16% efficiency from thick-film organic solar cells

Over 16% efficiency from thick-film organic solar cells

A blade-coated highly efficient thick active layer for non-fullerene organic solar cells

Highly efficient large-area thick-film organic solar cells were fabricated by blade-coating with finely controlling the molecular packing.

Fused‐Ring Acceptors with Asymmetric Side Chains for High‐Performance Thick‐Film Organic Solar Cells

A kind of new fused-ring electron acceptor, IDT-OB, bearing asymmetric side chains, is synthesized for high-efficiency thick-film organic solar cells. The introduction of asymmetric side chains can increase the solubility of acceptor molecules, enable the acceptor molecules to pack closely in a dislocated way, and form favorable phase separation when blended with PBDB-T. As expected, PBDB-T:IDT-OB-based devices exhibit high and balanced hole and electron mobility and give a high power conversion efficiency (PCE) of 10.12%. More importantly, the IDT-OB-based devices are not very sensitive to the film thickness, a PCE of 9.17% can still be obtained even the thickness of active layer is up to 210 nm.

A regioregular conjugated polymer for high performance thick-film organic solar cells without processing additive

Regioregular PTB7-Th with pre-designated repeat units achieves over 10% efficiency in thick-film solar cells without the assistance of a solvent additive.

Highly crystalline low-bandgap polymer nanowires towards high-performance thick-film organic solar cells exceeding 10% power conversion efficiency

One-dimensional low bandgap polymer nanowires successfully incorporated into bulk-heterojunction organic solar cells, yielding a high PCE exceeding 10% with thick films.

Solution processed thick film organic solar cells

In this Review article, significant advances in materials development and processing methods toward efficient solution processed bulk-heterojunction thick film organic solar cells as well as the factors that determine the optimal active layer thickness are summarized.