Asymmetric substitution of end‐groups is first applied in molecular donors. Three commonly used end‐groups of 2‐ethylhexyl cyanoacetate (CA), 2‐ethylhexyl rhodanine (Reh), and 1H‐indene‐1,3(2H)‐dione (ID) are combined to construct a series of symmetric and asymmetric donors. Correspondingly, the asymmetric donors SM‐CA‐Reh and SM‐CA‐ID show largely increased dipole moments (2.14 and 3.39 D, respectively) and enhanced aggregation propensity, as compared to those of symmetric donors of SM‐CA, SM‐Reh, and SM‐ID. Using N3 as acceptor, interestingly, SM‐CA‐Reh integrates the photovoltaic characteristics of high fill factor (FF) for SM‐CA and high short‐circuit current density for SM‐Reh, and delivers a record power conversion efficiency (PCE) of 16.34% with a high FF of 77.5%, which is much higher than 15.41% for SM‐CA and 14.76% for SM‐Reh. However, SM‐CA‐ID and SM‐ID give the lower PCE of 8.20% and 2.76%. Characterization results suggest that the π–π interaction mainly dictates the packing morphology of blend films instead of dipole effect or crystallinity. Mono‐substitution of Reh facilitates the molecular demixing appropriately but keeps the characteristic of the fine bicontinuous network of SM‐CA:N3. SM‐CA‐Reh:N3 shows more efficient exciton extraction, higher hole transport, and better miscibility. These results well explain the merits integration and improved photovoltaic performance.

Asymmetric Substitution of End‐Groups Triggers 16.34% Efficiency for All‐Small‐Molecule Organic Solar Cells

High-Efficiency Ternary Sequential Solution Deposition Structure Organic Solar Cells with Two Polymer Donors

Impact of fluorination of central thiophene linking core in thermostable perylene-diimide-based dimeric acceptors on molecular configuration and photovoltaic performance

Nonfullerene acceptors have boosted the power conversion efficiencies (PCE) of organic solar cells (OSCs). The rigid fused-ring molecular skeletons enable decent molecular planarity and stacking orientations, but suffer from tedious...

Rationally regulating π-bridge of small molecular acceptors for efficient organic solar cells

This paper provides a comprehensive overview of organic photovoltaic (OPV) cells, including their materials, technologies, and performance. In this context, the historical evolution of PV cell technology is explored, and the classification of PV production technologies is presented, along with a comparative analysis of first, second, and third-generation solar cells. A classification and comparison of PV cells based on materials used is also provided. The working principles and device structures of OPV cells are examined, and a brief comparison between device structures is made, highlighting their advantages, disadvantages, and key features. The various parts of OPV cells are discussed, and their performance, efficiency, and electrical characteristics are reviewed. A detailed SWOT analysis is conducted, identifying promising strengths and opportunities, as well as challenges and threats to the technology. The paper indicates that OPV cells have the potential to revolutionize the solar energy industry due to their low production costs, and ability to produce thin, flexible solar cells. However, challenges such as lower efficiency, durability, and technological limitations still exist. Despite these challenges, the tunability and versatility of organic materials offer promise for future success. The paper concludes by suggesting that future research should focus on addressing the identified challenges and developing new materials and technologies that can further improve the performance and efficiency of OPV cells.

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Advances in organic photovoltaic cells: a comprehensive review of materials, technologies, and performance

The evolution of small molecular acceptors for organic solar cells: Advances, challenges and prospects

Side-chain engineering has been acknowledged as one ingenious method to regulate material crystallinity, miscibility and microstructure to achieve favorable photovoltaic performance. Subtle changes of the side chains would have a...

Side-chain engineering improve molecular stacking and miscibility for efficient fullerene organic solar cells

Layer-by-layer solution-process enables higher crystallinity and desirable phase separation in non-fullerene organic solar cells

Electron transport layers (ETLs) are imperative in n-i-p structured perovskite solar cells (PSCs) because of their capability to affect light propagation, electron extraction, and perovskite crystallization, and any mismatch of optical constants, band position, and surface potential between the ETLs and the perovskites can cause unintentional optical and electrical losses. Herein, an antireflective and energetic cascade bilayer ETL with ubiquitously used SnO2 and TiO2 was constructed at 150 °C for PSCs, and the in-depth mechanism for performance improvement was systematically unraveled. It was revealed that the construction of an ETL with gradually increasing refractive indices can circumvent light reflection loss, resulting in enhanced photocurrent. The combined ETL forms an energetic cascade to promote electronic conductivity and facilitate electron extraction with reduced energy loss. Moreover, topologic perovskite growth with improved crystallinity and vertical orientation was preferred owing to the relative dewetting behavior, leading to reduced defect states and enhanced carrier mobility in the perovskite layer.

Xin Liang

Papers

The evolution of small molecular acceptors for organic solar cells: Advances, challenges and prospects

Side-chain engineering improve molecular stacking and miscibility for efficient fullerene organic solar cells

Layer-by-layer solution-process enables higher crystallinity and desirable phase separation in non-fullerene organic solar cells

Unraveling Optical and Electrical Gains of Perovskite Solar Cells with an Antireflective and Energetic Cascade Electron Transport Layer.

Enhancing thermal conductivity and chemical protection of bacterial cellulose/silver nanowires thin-film for high flexible electronic skin.