Chang Liu

Phosphonic acid-based self-assembled monolayers (SAMs) are widely used as hole-selective contacts in inverted perovskite solar cells. However, conventional deposition methods of SAMs inevitably leave physisorbed multilayers that contain under-protonated P-OH groups, which degrade the buried interface and hinder carrier extraction. Here, we report a dip-flush strategy using pyridine derivatives (3-fluoropyridine and 3-methoxypyridine) as mild coordinating solvents to selectively remove weakly bound species from dip-coated 4-(7H-dibenzo[c,g]carbazol-7-yl)butyl phosphonic acid SAMs. These pyridine derivatives exploit strong hydrogen-bond-accepting ability to preferentially interact with physisorbed molecules, thereby desorbing aggregates while leaving the chemisorbed monolayer intact. Density functional theory calculations confirm that 3-methoxypyridine exhibits superior cleaning efficacy owing to its stronger binding affinity and lower removal energy. The flush post-treatment significantly reduces residual P-OH groups and yields a cleaner, more hydrophobic, and smoother SAM surface. Consequently, perovskite films grown on the cleaned SAM show enhanced crystallinity and a void-free buried interface. As a result, the optimized dip-flush SAM delivers a champion power conversion efficiency of 26.49%, and this advantage scales up to a 12.87 cm2 (aperture area) mini-module, for which a PCE of 22.56% is obtained. This dip-flush chemically selective strategy offers a scalable pathway toward highperformance, largearea perovskite photovoltaics.

Wide‐bandgap (WBG) perovskites with a ∼1.78 eV bandgap are essential for monolithic all‐perovskite tandem cells, yet their efficiency and stability are limited by complex precursor chemistry, uncontrolled crystallization, defect formation, and photoinduced halide segregation. Here, we report 4‐(3‐Carbamimidoylguanidino)benzoic acid hydrochloride (CGBA) as a precursor‐level regulator for Cs/formamidinium (CsFA)‐based Br‐rich WBG perovskites. Through dynamic associations with lead–halide species and organic cations, CGBA modifies the local precursor environment and alters the stage‐dependent film‐formation behavior during spin coating and annealing. This regulation moderates crystallization, promotes texture development, reduces trap‐mediated nonradiative recombination, and suppresses photoinduced halide segregation. Consequently, the optimized 1.78 eV single‐junction device achieves a power conversion efficiency (PCE) of 21.43% and a fill factor (FF) of 85.89%, placing it among the highest reported FF values for 1.75–1.79 eV single‐junction WBG perovskite solar cells. The strategy is also transferable across multiple compositions and conditions, yielding efficiencies of 27.32% (1.53 eV), 23.91% (1.68 eV), 18.75% (1.85 eV), and 26.08% (1.58 eV, antisolvent‐free). Unencapsulated target devices retain 93% of their initial efficiency after 4500 h in N ₂ . When integrated into a monolithic all‐perovskite tandem, the CGBA‐optimized WBG subcell enables a laboratory‐measured PCE of 29.63%. This work establishes precursor‐level regulation as a transferable strategy for efficient and stable WBG perovskites and all‐perovskite tandems.

Tin–lead mixed perovskite solar cells (Sn–Pb PSCs), as a key component for all-perovskite tandem architectures, hold great promise for surpassing the efficiency limits of single-junction devices. However, the commonly used PEDOT:PSS hole transport layer (HTL) often limits the performance and stability of Sn–Pb PSCs because of its hygroscopic and acidic nature. To overcome this, we introduce a buried interface engineering strategy by incorporating two chiral molecules, namely (R)-2-amino-3-(2-hydroxyphenyl)propionic acid hydrochloride (HPA) and (R)-2-amino-3-(benzyloxy)propionic acid hydrochloride (HDS), directly into PEDOT:PSS. These additives not only mitigate hygroscopicity and improve the film uniformity of PEDOT:PSS but also effectively modify the buried interface. They regulate the quinoid structure ratio in PEDOT, optimize the HTL work function, and passivate interfacial defects, thereby enhancing charge extraction and promoting crystallization of the upper perovskite layer. As a result, the optimized devices exhibit significantly improved charge transport and suppressed carrier recombination, achieving remarkable power conversion efficiencies (PCEs) of 22.63% (HPA) and 23.23% (HDS), from a control value of 21.62%. These efficiencies are among the highest reported for Sn–Pb mixed PSCs to date and are accompanied by notably enhanced long-term stability. Furthermore, this approach enables a two-terminal all-perovskite tandem solar cell with an outstanding PCE of 28.48%, demonstrating its broad applicability to high-efficiency photovoltaic systems.

All‐perovskite tandem solar cells promise to surpass the Shockley–Queisser limit, but the buried interface between the hole transport layer (HTL) and narrow‐bandgap (NBG) Pb–Sn perovskite suffers from non‑radiative recombination, energy mismatch, and defects. Here, we use 3‑amino‑4‑hydroxybenzenesulfonic acid (APS) as a multifunctional dipolar molecule to engineer this interface. The sulfonate group anchors onto the HTL, creating oriented dipoles that tailor the electrostatic field; amino and hydroxyl groups synergistically passivate traps, coordinate undercoordinated Pb ^{2 +} and Sn ^{2 +} , inhibit Sn ^{2 +} oxidation, and modulate crystallization. This optimizes energy alignment, establishes a type‑II band structure and ohmic contact, suppresses recombination, and promotes carrier transport. Consequently, the APS‑modified single‑junction NBG Pb–Sn cell achieves a power conversion efficiency (PCE) of 24.02%, versus 22.21% for the control, and shows improved stability (retaining 86% of initial PCE after 2600 h in N ₂ ). Applying the same strategy to all‑perovskite tandem cells yields a PCE of 29.51%. This work provides a dipole‑mediated interface design that simultaneously addresses defect passivation, energy‑level tuning, and charge extraction, offering a promising pathway toward high‑efficiency and durable Pb–Sn mixed perovskite solar cells and their tandem architectures.

Widebandgap (WBG) perovskites are critical for highefficiency tandem solar cells but suffer from rapid crystallization, photoinduced halide segregation, and interfacial losses. We introduce methyl 2(4,4,5,5tetramethyl1,3,2dioxaborolan2yl)1Hindole7carboxylate (MHIC) as a multifunctional modulator for 1.68 eV WBG perovskites. Its methoxycarbonyl and boronate groups form Lewis acid–base and hydrogenbonding interactions with the perovskite lattice, effectively passivating defects, reinforcing the framework, and suppressing halide segregation via lattice stabilization. Concurrently, MHIC creates a favorable interfacial dipole that lowers the holeextraction barrier, while retarding nucleation and crystal growth to yield largegrained, lowdisorder films. Singlejunction inverted cells achieve a champion efficiency of 23.80% with an outstanding fill factor of 86.27% and negligible hysteresis—among the best reported for this bandgap. The strategy is universally effective across compositions from 1.25 to 1.85 eV, including 1.58 eV without antisolvent. Integrated into monolithic twoterminal tandems with TOPCon silicon bottom cells, devices reach 32.04% (0.9025 cm ² ). Unencapsulated cells exhibit markedly improved operational stability, retaining 95.26% of initial efficiency after 4500 h storage in nitrogen. This work offers a holistic molecularengineering approach that simultaneously tailors crystallization kinetics, electronic structure, and phase stability, providing a viable route to overcome the persistent efficiency–stability tradeoff in WBG perovskite photovoltaics.

Organic solar cells are among the most advanced thin‐film photovoltaic technologies due to their lightweight, thin, and flexible characteristics. However, an inherent trade‐off between open‐circuit voltage ( V _OC ) and short‐circuit current density ( J _SC ) exists, fundamentally stemming from the balance between charge generation and recombination. To address this challenge, we developed a two‐dimensional extension molecule based on the A‐D‐A′‐D‐A non‐fullerene acceptor (NFA) framework by replacing the central core with anthracene and introducing halogen‐free end groups, yielding a novel molecule named QxAt. This molecule combines high crystallinity with a complementary absorption spectrum to commonly used NFAs. When incorporated as a voltage‐current balancer into the PM6:BTP‐eC9 system, the active layer morphology was largely preserved, while molecular packing was modestly optimized, contributing to more efficient exciton dissociation and charge collection, improved hole and electron mobilities, and effective suppression of charge recombination, ultimately enabling a moderate improvement in J _SC . More importantly, QxAt significantly increased the electroluminescence quantum efficiency, effectively suppressing non‐radiative recombination and reducing energy loss, which in turn elevated V _OC . Consequently, the PCE was markedly improved from 18.9% to 20.1%, achieving a synergistic optimization of both V _OC and J _SC . This work provides a molecular design strategy to mitigate the voltage‐current trade‐off for high‐efficiency organic photovoltaics.

Organic solar cells (OSCs) based on non‐fullerene acceptors have achieved power conversion efficiencies (PCEs) exceeding 20%. However, their long‐term stability remains limited by uncontrolled molecular aggregation and morphological degradation in bulk heterojunction (BHJ) films. Here, we report a thiazole‐based acceptor (BDTTz) as a molecular packing reshaper that selectively regulates acceptor H‐aggregation to enable efficient and stable OSCs. Theoretical calculations reveal stronger interactions between BDTTz and L8‐BO than between BDTTz and PM6, enabling targeted reinforcement of acceptor packing without disrupting donor organization. Incorporating BDTTz into PM6:L8‐BO blends extends the acceptor crystallization window from 32 to 48 ms, increases the coherence length from 50.21 to 57.17 Å, and raises the glass‐transition temperature from 104°C to 142°C, thereby suppressing molecular diffusion and stabilizing the blend morphology. The optimized morphology facilitates charge transport, suppresses the nonradiative recombination, and mitigates the electron–phonon coupling, affording a champion PCE of 20.66% with an extended T ₈₀ lifetime of 1200 h under continuous illumination and heating conditions. Moreover, BDTTz incorporation into D18:L8‐BO blends yields a champion PCE of 21.08%. This work establishes a molecular‐level packing‐reshaping strategy for developing high‐efficiency and long‐term‐stable OSCs.

Organic solar cells (OSCs) based on non‐fullerene acceptors have achieved power conversion efficiencies (PCEs) exceeding 20%. However, their long‐term stability remains limited by uncontrolled molecular aggregation and morphological degradation in bulk heterojunction (BHJ) films. Here, we report a thiazole‐based acceptor (BDTTz) as a molecular packing reshaper that selectively regulates acceptor H‐aggregation to enable efficient and stable OSCs. Theoretical calculations reveal stronger interactions between BDTTz and L8‐BO than between BDTTz and PM6, enabling targeted reinforcement of acceptor packing without disrupting donor organization. Incorporating BDTTz into PM6:L8‐BO blends extends the acceptor crystallization window from 32 to 48 ms, increases the coherence length from 50.21 to 57.17 Å, and raises the glass‐transition temperature from 104°C to 142°C, thereby suppressing molecular diffusion and stabilizing the blend morphology. The optimized morphology facilitates charge transport, suppresses the nonradiative recombination, and mitigates the electron–phonon coupling, affording a champion PCE of 20.66% with an extended T ₈₀ lifetime of 1200 h under continuous illumination and heating conditions. Moreover, BDTTz incorporation into D18:L8‐BO blends yields a champion PCE of 21.08%. This work establishes a molecular‐level packing‐reshaping strategy for developing high‐efficiency and long‐term‐stable OSCs.

Inverted perovskite solar cells (PSCs) employing self‐assembled monolayers (SAMs) as hole‐selective contacts have achieved remarkable power conversion efficiencies. However, the inherent amphiphilicity of SAM molecules and persistent intermolecular O─H···O hydrogen bonding interactions stimulate molecular clustering, compromising monolayer uniformity and device performance. Herein, we introduce 5‐fluorobenzo[2,1,3]thiadiazole (5FBT), a planar molecule devoid of oxyacid groups, as a co‐adsorbent to modulate the 4‐(7H‐dibenzo[c,g]carbazol‐7‐yl)butyl)phosphonic acid (4PADCB) self‐assembled monolayer. The electron‐withdrawing benzothiadiazole core of 5FBT promotes π‐π coupling with 4PADCB, while its planar geometry disrupts O─H···O hydrogen bonding networks, suppressing molecular aggregation. Additionally, rigid 5FBT molecules adopt a tilted vertical orientation on ITO, serving as structural pillars that template 4PADCB assembly. This co‐adsorbent‐modulated SAM strategy improves monolayer uniformity and energy level alignment, constructing a high‐quality perovskite/SAMs interface. Consequently, the resulting PSCs achieve a champion efficiency of 26.67% and demonstrate superior operational stability, retaining 94.6% of their initial performance after 1000 h. The strategy is also readily scalable, delivering efficiency of 22.78% for 12.87 cm ² mini‐module. This work highlights mitigating hydrogen bond‐driven aggregation as a key design principle for efficient and stable SAM‐based PSCs.

Fibrillar networks formed during solution processing play a key role in the high performance of modern organic solar cells (OSCs). Yet their formation is intrinsically non-equilibrium and largely stochastic, leading to discontinuous domains and mismatched donor/acceptor interfaces that limit charge transport. Here, we show that the evolution of fibrillar networks can be guided through molecular design. By designing a cycloalkoxy-functionalized acceptor, O6R-4F, we create a molecular navigator that preferentially localizes at donor/acceptor interfaces, suppresses excessive self-aggregation of L8-BO-C₅ acceptor, and promotes coordinated donor/acceptor aggregation and crystallization during film formation. This results in finer, more interconnected fibrillar networks with improved phase separation. As-cast D18: L8-BO-C₅: O6R-4F devices achieve a power conversion efficiency of 20.9% without post-deposition treatment. The same approach also improves morphology and performance in chemically distinct donor/acceptor systems, demonstrating that controlling intermolecular interactions provides a general strategy for directing fibrillar network formation in solution-processed organic semiconductors.