Tao Wang

PIB with shear-thinning ability is introduced to facilitate ink spreading whilst also increasing the static viscosity to suppress both capillary and Marangoni flows after printing, yielding uniformity across a large area and delivering high PCEs.

Side-chain dipole interaction reinforces the backbone stacking and forms a Y-shape co-crystallized dimer. This dimer serves as the building block to form nanoscale fibrils for improved charge transport and eventually enhanced device performance.

Enhancing electron extraction and suppressing interfacial recombination are essential for achieving high‐performance inverted perovskite solar cells. However, the commonly used [6,6]‐phenyl‐C ₆₁ ‐butyric acid methyl ester (PCBM) electron transport layer (ETL) suffers from self‐aggregation during operation and possesses insufficient functional groups for perovskite passivation, which deteriorate charge collection and long‐term stability. Here, two C ₆₀ ‐terminated bis‐fullerene derivatives, namely C ₆₀ ‐IT‐C ₆₀ and C ₆₀ ‐L8BO‐C ₆₀ , are employed to modify the PCBM ETL. These additives preserve high compatibility with PCBM and feature π‐conjugated bridge‐linkers that can regulate the intermolecular interactions with PCBM as well as the interfacial defect passivation toward perovskite. Compared with the IT‐bridged molecule, C ₆₀ ‐L8BO‐C ₆₀ , featuring a more rigid and extended dithienothiophen[3,2‐b]‐pyrrolobenzothiadiazole (TPBT) bridge, enables more extensive π‐conjugated contacts with surrounding PCBM molecules and more effective interfacial passivation, leading to enhanced electron mobility, reduced trap density, and accelerated interfacial electron extraction. As a result, the unencapsulated C ₆₀ ‐L8BO‐C ₆₀ ‐based inverted device achieves a power conversion efficiency of 25.40%, and retains 80% of its initial efficiency after more than 1400 h of continuous thermal aging at 85°C in a N ₂ atmosphere in the dark.

Organic solar cells (OSCs) suffer from substantial energy losses arising from strong electron‐phonon coupling and structural relaxation, which limit their open‐circuit voltage. Conjugation extension has recently been employed to rigidify molecular backbones and suppress non‑radiative recombination; however, conventional fused‑ring extension often induces excessive aggregation that compromises the short‑circuit current density and fill factor. Here, we report a non‑fused conjugation extension strategy that simultaneously enhances molecular rigidity and optimizes intermolecular packing in small molecular acceptors. By extending the central core with a single thiophene group and introducing an intramolecular F···S conformational lock, the resulting acceptor C5Qx‐FTh achieves a nearly coplanar conformation with a dihedral angle below 1°. This rigidified framework suppresses the electron‐phonon coupling and reduces the excitonic static disorder, while also suppressing molecular chain dynamics and enhancing device stability. Theoretical simulations and morphological characterizations reveal that this non‑fused conjugation extension enlarges the intermolecular interaction area (from 302 to 342 Å ² ) and promotes the transition from A‐to‐A to A‐to‐D packing motifs, leading to tighter molecular stacking with shortened π‐π and lamellar distances. Consequently, the PM6:C5Qx‐FTh binary device achieves a remarkable PCE of 20.1% with a low nonradiative energy loss of 0.18 eV.

Oligomerized non‐fullerene acceptors (o‐NFAs) have emerged as a promising material for constructing efficient and stable organic solar cells (OSCs). However, the precise role of their molecular geometry and surface properties in governing the vertical phase distribution for efficient charge collection near electrodes of OSCs remains underexplored. In this work, two trimerized star‐shaped oligomer acceptors, TAQ‐15F and TBQ‐15F, are synthesized with fused and non‐fused trithiophene‐benzene cores. We find although this core modulation barely affects the energy levels and absorption spectra, it substantially changes the surface free energy of these o‐NFAs and consequently influences their vertical phase distribution within the photoactive layer. With a more twisted conformation, TBQ‐15F allows its side chains to be ordered in out‐of‐plane and results in a much lower surface free energy compared to TAQ‐15F. When TBQ‐15F is incorporated into the classic D18/L8‐BO photoactive layer via layer‐by‐layer deposition, this reduced surface energy further correlates a more pronounced vertical stratification and gradient molecular distribution (acceptor‐rich near the cathode and donor‐rich near the anode) as revealed by angle‐dependent GIWAXS measurements and XPS depth profiling. Certified power conversion efficiency (PCE) of 20.8% with improved operational stability was achieved in the D18/L8‐BO+TBQ‐15F ternary OSCs.

Achieving high power conversion efficiency (PCE) and operational stability remains a critical challenge of organic solar cells (OSCs). While the 2PACz self‐assembled monolayer (SAM) offers suppressed parasitic absorption and facilitated charge collection over the routinely‐used PEDOT:PSS hole‐transport layer (HTL), their operational stability is often limited by the vulnerable chemical structure under high‐energy photon illumination. In this work, we design and synthesize two SAMs, PhPACz and ThPACz, whose flexible alkyl linker between phosphonic acid and carbazole of 2PACz is substituted by rigid phenyl or thiophene to manipulate the HOMO and LUMO orbitals and further mediate the electron density distribution of SAM, thereby promoting charge delocalization at the interface and enhancing photochemical stability. The ThPACz SAM delivers suppressed oxygen defects on the ITO surface and largely enhanced the bond dissociation energy at the vulnerable C‐N bond (from 72.2 kcal/mol in 2PACz to 97.3 kcal/mol in ThPACz), translating to a champion efficiency of 20.5% in D18:L8‐BO binary OSCs, alongside a significantly extended T ₈₀ lifetime (over 7 times) under either visible or 365 nm UV light, outperforming the 2PACz based benchmark. This study underscores the critical role of conjugated linkers in designing high‐performance, stable SAMs for next‐generation OSCs.

Additive engineering offers a simple and efficient way to enhance the structural order of organic semiconductors, yet the interplays between their molecular structural and interactions remains unclear. Herein, two sets of additives, including conformationally rigid DTCO-2Br and DTC and conformationally flexible INF-TC and BT-TC, featuring opposite electrostatic potentials (ESPs), are designed. For PM6, both ESP complementarity and conformational flexibility are effective in tuning the molecular packing, while the conformational flexible INF-TC with opposite ESP not only enhances the structural order but also shortens the π–π stacking distance. For the relatively rigid L8-BO, conformational flexibility is essential to adjust the intermolecular interaction. As such, only conformational flexible INF-TC and BT-TC improve the lamellar stacking of L8-BO, and the ESP complementary BT-TC demonstrates the strongest effect. By applying INF-TC in the donor layer and BT-TC in the acceptor layer, improved efficiency and morphological stability were achieved, with a maximum efficiency of 20.4% achieved in the D18/L8-BO system.

With the rapid development of the A‐D‐A type non‐fullerene electron acceptors (NFAs), organic solar cells (OSCs) have exhibited remarkable progress in the last decade, with power conversion efficiency (PCE) reaching 21%. However, compared with the traditional inorganic Si photovoltaics, OSCs still show inferior PCE and operational stability, hindering its commercialization. By substituting the indanone structured end groups of cutting‐edge NFA L8‐BO with C ₆₀ cage, this work prepares a novel C ₆₀ terminated acceptor–donor–acceptor (A–D–A) type electron acceptor, C ₆₀ ‐L8BO‐C ₆₀ . Compared with the traditional spherical fullerene PC ₆₁ BM, C ₆₀ ‐L8BO‐C ₆₀ exhibits significantly improved miscibility with both polymer donors and NFAs, enabling it to tune the donor/acceptor interfacial interactions and suppress their phase separation under device operation. As the results, by incorporating 5% of C ₆₀ ‐L8BO‐C ₆₀ as a guest component, increased exciton dissociation efficiency with suppressed carrier recombination is received, leading to a maximum efficiency of 20.6% (certified PCE of 20.25%) in a D18:L8‐BO:C ₆₀ ‐L8BO‐C ₆₀ based device. The university of C ₆₀ ‐L8BO‐C ₆₀ in enhancing the efficiency and stability is also verified in a range of polymer:non‐fullerene systems, and delivering a significantly improved operational T ₈₀ lifetime of 200% (270 to 815 h) under a standardized ISOS‐L‐3 harsh stability measurement (65 ± 5°C, 65 ± 10% RH, one‐sun illumination).

Oligomeric acceptors have emerged as one of the promising alternatives for constructing high‐performance and stable organic solar cells (OSCs). Among them, star‐shaped oligomers are particularly noteworthy due to their unique 3D architecture, which facilitates multi‐dimensional molecular packing and charge transport. Nevertheless, this class of materials has received relatively limited attention to date, and molecular design strategies to optimize their photophysical and morphological properties remain underexplored. Herein, we designed and synthesized a novel star‐shaped trimeric acceptor, T‐NIC, based on a benzotrithiophene (BTT) central core and conjugated‐extended naphthalene‐based terminal groups. Compared to its benzene‐capped analogue T‐IC, T‐NIC exhibits broadened absorption, enhanced molecular packing, and a higher glass transition temperature ( T g). The binary device PM6:T‐NIC exhibits a power conversion efficiency (PCE) of 18.94% and demonstrates exceptional stability by maintaining 80% of its initial performance over 1380 h of continuous illumination. Crucially, the introduction of T‐NIC into the PM6:BTP‐eC9 host system results in a ternary device with a high PCE of 20.36%. The observed efficiency enhancement originates from the synergistic interplay of an optimized blend morphology and enhanced molecular packing. This study demonstrates that terminal group conjugation extension in trimer acceptors offers a powerful and synergistic strategy for simultaneously increasing the efficiency and device stability.