Breaking through efficiency barriers with innovative three-component systems
Imagine if solar panels could be as thin as paper, as flexible as fabric, and as cheap to produce as newspaper—all while generating electricity efficiently. This isn't science fiction; it's the promise of polymer solar cells, a groundbreaking technology that's rapidly transforming our approach to renewable energy.
Significantly lighter than traditional silicon panels
Can be integrated into curved surfaces and flexible devices
Potential for low-cost mass production through printing techniques
While traditional silicon solar panels have dominated the market for decades, they're rigid, heavy, and energy-intensive to manufacture. Polymer solar cells offer a compelling alternative with their lightweight properties, flexibility, and potential for low-cost mass production through simple printing techniques 1 .
Despite these advantages, polymer solar cells have faced a significant hurdle: capturing sunlight efficiently across the full spectrum of colors that make up solar light. Most organic materials used in these cells absorb light only within a narrow range of wavelengths, like a musician who can only play one note. For years, scientists struggled with this limitation in binary blend solar cells, which combine one electron-donating polymer with one electron-accepting molecule. Then, researchers had a breakthrough—what if they added a third component to the mix? This innovation led to the development of ternary nonfullerene polymer solar cells 1 .
To understand the significance of ternary solar cells, we first need to examine the limitations of their binary predecessors.
The ternary approach effectively adds a "third musician" to the solar cell ensemble—a component that can play the notes the original duo couldn't. This third component, strategically chosen to have complementary absorption properties, allows the solar cell to harvest photons across a much broader range of the solar spectrum 1 4 .
Ternary polymer solar cells typically incorporate a carefully selected third component into a host binary system. This addition creates a sophisticated energy network that enhances solar cell performance through several mechanisms.
The third component expands light-harvesting capability by absorbing different wavelengths than the host system 4 .
The third component improves nanoscale structure for better charge separation and transport 3 .
Step-wise energy alignment enables efficient electron transfer
For instance, in the PM6:Y6 system, the addition of a highly crystalline third component was shown to enhance crystallinity while reducing phase separation, leading to prolonged carrier lifetime and more efficient exciton transport 3 .
A groundbreaking study published in 2025 exemplifies how strategic material selection in ternary systems can achieve remarkable efficiency breakthroughs 9 .
Researchers synthesized a novel wide-bandgap polymer donor called P(BTzE-BDT) and incorporated it into the well-known PM6:BTP-eC9 binary system.
Researchers designed and synthesized P(BTzE-BDT) with specific molecular features to ensure complementary absorption and good compatibility with the host PM6 donor polymer.
Ternary organic solar cells were fabricated with a standard inverted structure: ITO/ZnO/active layer/MoO₃/Ag. The active layer contained PM6:BTP-eC9 with varying small amounts of P(BTzE-BDT) added.
The team carefully optimized the ratio of the three components, finding that 5% P(BTzE-BDT) content yielded the best performance.
Extensive tests were conducted to evaluate the optical properties, morphological changes, charge dynamics, and overall device performance.
The results were impressive. The ternary device with 5% P(BTzE-BDT) achieved a record-breaking power conversion efficiency of 20.0%, compared to 18.8% for the binary reference device.
| Device Type | PCE (%) | JSC (mA/cm²) | VOC (V) | FF (%) |
|---|---|---|---|---|
| Binary (PM6:BTP-eC9) | 18.8 | 26.8 | 0.854 | 76.1 |
| Ternary (with 5% P(BTzE-BDT)) | 20.0 | 27.4 | 0.858 | 77.4 |
Table 1: Performance Comparison of Binary vs. Ternary Devices 9
| Device Type | PCE (%) | JSC (mA/cm²) | VOC (V) | FF (%) |
|---|---|---|---|---|
| Binary | 16.3 | 25.2 | 0.846 | 70.2 |
| Ternary | 18.2 | 26.5 | 0.852 | 74.1 |
Table 2: Thick-Film Device Performance (300 nm active layer) 9
The ternary device maintained a high efficiency of 18.2% even with an active layer thickness of 300 nm, significantly outperforming the binary device (16.3%) at this thickness 9 . This demonstration of thickness resilience indicates strong potential for large-scale, industrial manufacturing.
The remarkable progress in ternary polymer solar cells has been enabled by sophisticated material design. Here are some of the key research reagents and materials driving these advances.
| Material Name | Type | Function & Significance |
|---|---|---|
| PM6 | Polymer Donor | A widely studied donor material with suitable energy levels and good compatibility with various acceptors 3 . |
| Y6 and Derivatives | Nonfullerene Acceptor | A landmark acceptor family with strong near-infrared absorption and tunable energy levels 3 . |
| P(BTzE-BDT) | Wide-bandgap Polymer Donor | Novel guest donor that optimizes morphology through enhanced molecular packing 9 . |
| ITIC | Nonfullerene Acceptor | Early NFA that enables extended absorption to near-infrared regions and forms cascade energy levels 4 . |
| PCBM | Fullerene Acceptor | Traditional acceptor material; now often used in ternary blends to improve morphology 1 6 . |
| PFFO-Th | Polymer Acceptor | Third-component acceptor that enhances light harvesting and charge transport in all-polymer systems . |
| Chlorobenzene/o-Xylene | Processing Solvent | Solvents used for film processing; movement toward eco-friendly solvents like o-xylene . |
| 1,8-diiodooctane (DIO) | Processing Additive | Additive that optimizes blend morphology by controlling crystallization and phase separation 4 . |
Table 3: Essential Materials in Ternary Solar Cell Research
The strategic combination of these materials enables researchers to fine-tune the optical, electronic, and morphological properties of ternary blends, pushing the efficiency limits of polymer solar cells ever higher.
The advancements in ternary polymer solar cells open up exciting possibilities for real-world applications.
Semitransparent, flexible solar cells could be integrated into windows, facades, and roofing materials.
Lightweight and flexible solar cells could power smart clothing, fitness trackers, and other wearable devices.
Foldable or rollable solar chargers for mobile devices, particularly useful for outdoor activities and emergency power.
Self-powered sensors and devices that can operate independently of the electrical grid.
Current high-performance devices often require halogenated solvents that pose environmental and health risks. Research is increasingly focused on developing ternary systems that can be processed with eco-friendly solvents .
These systems offer enhanced mechanical flexibility and stability, making them ideal for flexible applications. Recent work has demonstrated all-polymer ternary solar cells with efficiencies approaching 19% .
Improving the operational stability of ternary solar cells remains a crucial challenge. Research into more stable material combinations and encapsulation techniques is ongoing.
The vast design space for ternary blends—with countless possible material combinations—makes them ideal candidates for AI-driven materials discovery 2 .
Ternary polymer solar cells represent a brilliant solution to one of the most persistent challenges in organic photovoltaics—how to efficiently capture the full spectrum of sunlight using organic materials. By strategically combining two polymer donors with an organic semiconductor acceptor, researchers have created systems that leverage complementary absorption, cascade energy levels, and optimized morphology to achieve unprecedented efficiencies.
The recent achievement of 20% efficiency marks a significant milestone, bringing polymer solar cells closer to commercial competitiveness with traditional silicon photovoltaics, but with added benefits of flexibility, light weight, and transparency. As research advances in green processing, stability enhancement, and novel material design, we move closer to a future where solar energy collection is seamlessly integrated into our everyday environments—from the clothes we wear to the windows in our homes.
The journey of ternary polymer solar cells exemplifies how creative molecular engineering can overcome fundamental limitations, turning what was once a laboratory curiosity into a technology with genuine potential to transform our energy landscape.