The past decade has witnessed significant advances in the field of organic solar cells (OSCs). Ongoing improvements in the power conversion efficiency of OSCs have been achieved, which were mainly ...attributed to the design and synthesis of novel conjugated polymers with different architectures and functional moieties. Among various conjugated polymers, the development of wide‐bandgap (WBG) polymers has received less attention than that of low‐bandgap and medium‐bandgap polymers. Here, we briefly summarize recent advances in WBG polymers and their applications in organic photovoltaic (PV) devices, such as tandem, ternary, and non‐fullerene solar cells. Addtionally, we also dissuss the application of high open‐circuit voltage tandem solar cells in PV‐driven electrochemical water dissociation. We mainly focus on the molecular design strategies, the structure‐property correlations, and the photovoltaic performance of these WBG polymers. Finally, we extract empirical regularities and provide invigorating perspectives on the future development of WBG photovoltaic materials.
The development of wide‐bandgap (WBG) polymers is of significant importance in boosting the power conversion efficiency of organic solar cells. Recent advances in WBG polymers and their applications in different types of organic photovoltaic devices are reviewed. In addition, empirical regularities and invigorating perspectives are provided to help guide future designs of WBG photovoltaic materials.
Morphology control in laboratory and industry setting remains as a major challenge for organic solar cells (OSCs) due to the difference in film-drying kinetics between spin coating and the printing ...process. A two-step sequential deposition method is developed to control the active layer morphology. A conjugated polymer that self-assembles into a well-defined fibril structure is used as the first layer, and then a non-fullerene acceptor is introduced into the fibril mesh as the second layer to form an optimal morphology. A benefit of the combined fibril network morphology and non-fullerene acceptor properties was that a high efficiency of 16.5% (certified as 16.1%) was achieved. The preformed fibril network layer and the sequentially deposited non-fullerene acceptor form a robust morphology that is insensitive to the polymer batches, solving a notorious issue in OSCs. Such progress demonstrates that the utilization of polymer fibril networks in a sequential deposition process is a promising approach towards the fabrication of high-efficiency OSCs.
Non-fullerene acceptors have recently attracted tremendous interest because of their potential as alternatives to fullerene derivatives in bulk heterojunction organic solar cells. However, the power ...conversion efficiencies (PCEs) have lagged far behind those of the polymer/fullerene system, mainly because of the low fill factor (FF) and photocurrent. Here we report a novel perylene bisimide (PBI) acceptor, SdiPBI-Se, in which selenium atoms were introduced into the perylene core. With a well-established wide-band-gap polymer (PDBT-T1) as the donor, a high efficiency of 8.4% with an unprecedented high FF of 70.2% is achieved for solution-processed non-fullerene organic solar cells. Efficient photon absorption, high and balanced charge carrier mobility, and ultrafast charge generation processes in PDBT-T1:SdiPBI-Se films account for the high photovoltaic performance. Our results suggest that non-fullerene acceptors have enormous potential to rival or even surpass the performance of their fullerene counterparts.
The development of organic solar cells (OSCs) with thick active layers is of crucial importance for the roll-to-roll printing of large-area solar panels. Unfortunately, increasing the active layer ...thickness usually results in a significant reduction in efficiency. Herein, we fabricated efficient thick-film OSCs with an active layer consisting of one polymer donor and two non-fullerene acceptors. The two acceptors were found to possess enlarged exciton diffusion length in the mixed phase, which is beneficial to exciton generation and dissociation. Additionally, layer by layer approach was employed to optimize the vertical phase separation. Benefiting from the synergetic effects of enlarged exciton diffusion length and graded vertical phase separation, an efficiency of 17.31% (certified value of 16.9%) is obtained for the 300 nm-thick OSC, with a short-circuit current density of 28.36 mA cm
, and a high fill factor of 73.0%. Moreover, the device with an active layer thickness of 500 nm also shows an efficiency of 15.21%. This work provides valuable insights into the fabrication of OSCs with thick active layers.
Carbon emissions from the Yangtze River Economic Belt are an important element of China’s carbon emission endeavor, and a study of its emission reduction pathway can provide a reference for the ...country’s overall management of carbon emission reduction. From the perspective of energy consumption, this paper uses the carbon emission factor method to estimate the carbon emissions of the transportation industry in the Yangtze River Economic Belt during 2006–2020, based on the extended STIRPAT model, considering the influence of seven factors, i.e., population size, urbanization rate, GDP per capita, transportation added value, energy structure, energy intensity, and transportation intensity, on carbon emissions. Based on these factors, a scenario analysis, combined with a forecasting model, is used to predict the peak carbon performance of the transportation industry under different development scenarios. The results show that the overall carbon emissions of transportation in the YEB from 2006 to 2020 show a fluctuating upward trend, and the downstream carbon emissions are significantly higher than those in other regions. The main factors influencing carbon emissions from transportation in different upstream, midstream, and downstream regions vary, with both population and economic factors contributing to carbon emissions, while technical factors affect them differently. There are significant differences in the peak carbon performance of transportation under different development scenarios, and the government should take effective measures to work towards achieving the goals of the low-carbon or enhanced low-carbon scenarios.
A polymer fibril assembly can dictate the morphology framework, in forming a network structure, which is highly advantageous in bulk heterojunction (BHJ) organic solar cells (OSCs). A fundamental ...understanding of how to manipulate such a fibril assembly and its influence on the BHJ morphology and device performance is crucially important. Here, a series of donor–acceptor polymers, PBT1‐O, PBT1‐S, and PBT1‐C, is used to systematically investigate the relationship between molecular structure, morphology, and photovoltaic performance. The subtle atom change in side chains is found to have profound effect on regulating electronic structure and self‐assembly of conjugated polymers. Compared with PBT1‐O and PBT1‐S, PBT1‐C‐based OSCs show much higher photovoltaic performance with a record fill factor (FF) of 80.5%, due to the formation of optimal interpenetrating network morphology. Such a fibril network strategy is further extended to nonfullerene OSCs using a small‐molecular acceptor, which shows a high efficiency of 12.7% and an FF of 78.5%. The results indicate the formation of well‐defined fibrillar structure is a promising approach to achieving a favorable morphology in BHJ OSCs.
Three novel polymers are synthesized to systematically investigate the relationship between molecular structure, morphology, and photovoltaic performance. A favorable fibrillar network morphology with a narrow polymer fibril width in a PBT1‐C:PC71BM blend leads to a record fill factor exceeding 80%, indicating that the formation of a well‐defined fibrillar structure is a promising approach to achieving a favorable morphology in organic solar cells.
Ternary organic solar cells are promising alternatives to the binary counterpart due to their potential in achieving high performance. Although a growing number of ternary organic solar cells are ...recently reported, less effort is devoted to morphology control. Here, ternary organic solar cells are fabricated using a wide‐bandgap polymer PBT1‐C as the donor, a crystalline fused‐ring electron acceptor ITIC‐2Cl, and an amorphous fullerene derivative indene‐C60 bisadduct (ICBA) as the acceptor. It is found that ICBA can disturb π–π interactions of the crystalline ITIC‐2Cl molecules in ternary blends and then help to form more uniform morphology. As a result, incorporation of 20% ICBA in the PBT1‐C:ITIC‐2Cl blend enables efficient charge dissociation, negligible bimolecular recombination, and balanced charge carrier mobilities. An impressive power conversion efficiency (PCE) of 13.4%, with a high fill factor (FF) of 76.8%, is eventually achieved, which represents one of the highest PCEs reported so far for organic solar cells. The results manifest that the adoption of amorphous fullerene acceptor is an effective approach to optimizing the ternary blend morphology and thereby increases the solar cell performance.
Ternary organic solar cells based on a wide‐bandgap polymer donor (PBT1‐C), a fullerene derivative indene‐C60 bisadduct (ICBA), and a crystalline fused‐ring electron acceptor (ITIC‐2Cl) yield an impressive efficiency of 13.4%, and a high fill factor of 76.8%, indicating that the use of an amorphous fullerene acceptor is an effective way to optimize the ternary blend morphology.
Transportation carbon emission reduction has become an important driving point for China to achieve carbon peak and carbon neutrality. Based on the three-dimensional grey correlation analysis model, ...taking the five factors affecting transportation carbon emissions, namely, population, GDP, tertiary industry, energy structure and logistics scale, as the research object, the transportation carbon emissions of China’s low-carbon pilot and nonpilot provinces from 2010 to 2019 are calculated based on the Intergovernmental Panel on Climate Change (IPCC) carbon emission accounting method. The time series grey correlation degree and regional grey correlation degree of each influencing factor and traffic carbon emission are obtained using the provincial data, so as to provide policy suggestions for China to achieve the goal of “carbon peak and carbon neutrality” in the field of transportation. The results show that the descending order of the five influencing factors on transportation carbon emissions is: energy structure, logistics scale, population, GDP and tertiary industry. From 2010 to 2019, the time series grey correlation degree between the five influencing factors and transportation carbon emissions shows a fluctuating downward trend, but the impact of demographic factors has become more and more obvious in the past two years; According to the difference of grey correlation degree in different regions, the traffic development of various provinces in China is different, so it is necessary to formulate relevant policies individually.
The integration of high charge carrier mobility and high luminescence in an organic semiconductor is challenging. However, there is need of such materials for organic light-emitting transistors and ...organic electrically pumped lasers. Here we show a novel organic semiconductor, 2,6-diphenylanthracene (DPA), which exhibits not only high emission with single crystal absolute florescence quantum yield of 41.2% but also high charge carrier mobility with single crystal mobility of 34 cm(2) V(-1) s(-1). Organic light-emitting diodes (OLEDs) based on DPA give pure blue emission with brightness up to 6,627 cd m(-2) and turn-on voltage of 2.8 V. 2,6-Diphenylanthracene OLED arrays are successfully driven by DPA field-effect transistor arrays, demonstrating that DPA is a high mobility emissive organic semiconductor with potential in organic optoelectronics.
The blossoming of organic solar cells (OSCs) has triggered enormous commercial applications, due to their high‐efficiency, light weight, and flexibility. However, the lab‐to‐manufacturing translation ...of the praisable performance from lab‐scale devices to industrial‐scale modules is still the Achilles' heel of OSCs. In fact, it is urgent to explore the mechanism of morphological evolution in the bulk heterojunction (BHJ) with different coating/printing methods. Here, a general approach to upscale flexible organic photovoltaics to module scale without obvious efficiency loss is demonstrated. The shear impulse during the coating/printing process is first applied to control the morphology evolution of the BHJ layer for both fullerene and nonfullerene acceptor systems. A quantitative transformation factor of shear impulse between slot‐die printing and spin‐coating is detected. Compelling results of morphological evolution, molecular stacking, and coarse‐grained molecular simulation verify the validity of the impulse translation. Accordingly, the efficiency of flexible devices via slot‐die printing achieves 9.10% for PTB7‐Th:PC71BM and 9.77% for PBDB‐T:ITIC based on 1.04 cm2 . Furthermore, 15 cm2 flexible modules with effective efficiency up to 7.58% (PTB7‐Th:PC71BM) and 8.90% (PBDB‐T:ITIC) are demonstrated with satisfying mechanical flexibility and operating stability. More importantly, this work outlines the shear impulse translation for organic printing electronics.
A general approach for lab‐to‐manufacturing translation is developed to achieve high‐performance flexible organic solar modules without obvious efficiency loss. The shear impulse during the coating/printing process is applied to control the morphology evolution of the bulk heterojunction layer for both fullerene and nonfullerene acceptor systems. A quantitative transformation factor of shear impulse between slot‐die printing and spin‐coating is detected.
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