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Charge transport in the active layer, which can be effectively modulated by molecular doping of organic semiconductors, significantly affects the photovoltaic performance of organic solar cells (OSCs). However, it is difficult to control the dopant distribution in the bulk heterojunction (BHJ) films, which hinders efficient doping in OSCs. Herein, an effective n‐doping strategy is developed via sequential deposition (SD) of D18 donor and doped acceptor. The favorable vertical component distribution in SD films helps to optimize carrier transport pathways. The SD method confines the n‐dopant N‐DMBI to the acceptor layer, allowing positive effects of molecular doping. Consequently, the doped SD device exhibits superior charge transport with suppressed charge recombination, lower trap density, and enhanced charge extraction compared to the undoped one, resulting in a high power conversion efficiency of 19.55% for D18/L8‐BO binary OSCs. In addition, the doping does not affect the thermal stability of the devices, with the doped SD device retaining over 90% of its initial efficiency after 1200 h of heating at 80 °C. The universality of the SD doping method is also verified in other non‐fullerene acceptor systems. These results demonstrate the great potential of SD doping strategy for building high‐performance OSCs with enhanced charge transport. [ABSTRACT FROM AUTHOR]

Localized excitation in traditional organic photocatalysts typically prevents the generation and extraction of photo‐induced free charge carriers, limiting their activity enhancement under illumination. Here, we enhance delocalized photoexcitation of small molecular photovoltaic catalysts by weakening their electron‐phonon coupling via rational fluoro‐substitution. The optimized 2FBP‐4F catalyst we develop here exhibits a minimized Huang–Rhys factor of 0.35 in solution, high dielectric constant and strong crystallization in the solid state. As a result, the energy barrier for exciton dissociation is decreased, and more importantly, polarons are unusually observed in 2FBP‐4F nanoparticles (NPs). With the increased hole transfer efficiency and prolonged charge carrier lifetime highly related to enhanced exciton delocalization, the PM6 : 2FBP‐4F heterojunction NPs at varied concentration exhibit much higher optimized photocatalytic activity (207.6–561.8 mmol h−1 g−1) for hydrogen evolution than the control PM6 : BP‐4F and PM6 : 2FBP‐6F NPs, as well as other reported photocatalysts under simulated solar light (AM 1.5G, 100 mW cm−2). [ABSTRACT FROM AUTHOR]

The limited exciton diffusion length (LD) of organic semiconductors constraints exciton dissociation in pseudo-planar heterojunction (PPHJ) organic solar cells (OSCs), which is deemed the bottleneck hampering the further improvement in their power conversion efficiencies (PCEs). Herein, a solid-additive strategy was proposed to efficiently prolong the LD in PPHJ OSCs by developing a volatile solid additive, SA-5F, and blending it in non-fullerene acceptors. The addition of SA-5F endowed a Y6+ film with improved crystallinity and more compact molecular stacking, resulting in a higher photoluminescence quantum yield, larger overlap between its absorption and emission spectra, and shorter intermolecular distance compared with a pristine Y6 film. Thus, the Y6+ film achieved a higher exciton diffusion coefficient of 1.36 × 10−3 cm2 s−1 and, thus, ∼24% improvement in the LD to 10.27 nm. The prolonged LD enabled D18/Y6+-based PPHJ devices to realize more efficient exciton dissociation and weaker charge recombination compared with their D18/Y6 counterparts. Therefore, D18/Y6+-based PPHJ OSCs afforded an impressive PCE of 19.11%, which is among the highest values reported to date. Moreover, this strategy exhibits excellent universality in improving the photovoltaic performance of different systems. Thus, it was demonstrated that introducing a solid additive is an efficient and universal strategy to prolong the LD in PPHJ OSCs and consequently boost their PCEs. [ABSTRACT FROM AUTHOR]

In this work, a new electron-accepting unit has been designed through introducing two F atoms simultaneously at α,β-positions of the thiophene fused benzotriazole unit (ffBTAZT) to build a new D–A type polymer donor (PffBTAZT-fBDT) with -4,8-bis(5-alkyl-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene unit (fBDT) as an electron-donating unit. Different from the mono α-fluorinated thiophene-fused benzotriazole (fBTAZT) unit, another F atom introduced at the β-position of the fused thiophene ring of the fBTAZT unit can build an "F⋯HC" non-covalent interaction with its adjacent thiophene ring as a "π-bridge" to partially lock the conformation of the conjugated backbone and strengthen the rigidity of the molecular skeleton, which is favorable for the light harvesting efficiency and the charge mobility to improve the short-circuit current density (JSC). At the same time, the introduction of a strongly electronegative F atom can further reduce the HOMO energy level of the polymer donor, which is also favorable for the enhancement of the open-circuit voltage (VOC). Therefore, the photovoltaic performances of the PffBTAZT-fBDT based OSCs with Y6 acceptor have been comprehensively improved compared with PfBTAZT-fBDT based OSCs, in which the corresponding JSC, VOC, fill factor (FF) and photoelectric conversion efficiency (PCE) have been increased from 23.68 to 25.43 mA cm−2, 0.633 to 0.817 V, 58.46 to 69.94% and 8.77 to 14.53%, respectively. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Organic solar cells (OSCs) present a promising renewable energy technology due to their cost‐effectiveness, adaptability, and lightweight nature. The advent of non‐fullerene acceptors has further boosted their significance, allowing for power conversion efficiencies surpassing 19% even with an active layer thickness of about 100 nm. However, in order to achieve large scale production, it is necessary to fabricate OSCs with thicker active layers exceeding 300 nm that are compatible with large‐area printing techniques. Nevertheless, OSCs with thick active layers have inferior performance compared to those with thin active layers. To expedite the transition of OSCs from laboratory to industrial high‐throughput manufacturing, considerable efforts have been made to comprehend the performance limitations of thick active‐layer OSCs, develop novel photoactive materials that are high‐performance and tolerant towards the thickness of the active layer, and optimize the morphology of the photoactive layer and device structure. This review aims to provide a comprehensive summary of the mechanisms that lead to efficiency loss in thick active‐layer OSCs, the representative works on molecular design, and the optimization strategies for high‐performance thick active‐layer OSCs, and the remaining challenges that must be addressed. [ABSTRACT FROM AUTHOR]

For the process of photovoltaic conversion in organic solar cells (OSCs) and quantum‐dot solar cells (QDSCs), three of four steps are determined by exciton behavior, namely, exciton generation, exciton diffusion, and exciton dissociation. Therefore, it is of great importance to regulate exciton behavior in OSCs and QDSCs for achieving high power conversion efficiency. Due to the rapid development in materials and device fabrication, great progress has been made to manage the exciton behavior to achieve prolonged exciton diffusion length and improved exciton dissociation in recent years. In this review, we first introduce the parameters that affect exciton behavior, followed by the methods to measure exciton diffusion length. Then, we provide an overview of the recent advances with regard to exciton behavior investigation in OSCs and QDSCs, including exciton lifetime, exciton diffusion coefficient, and exciton dissociation. Finally, we propose future directions in deepening the understanding of exciton behavior and boosting the performance of OSCs and QDSCs. [ABSTRACT FROM AUTHOR]

The bulk heterojunction (BHJ) morphology of photovoltaic materials is crucial to the fundamental optoelectronic properties of organic solar cells (OSCs). However, in the photoactive layer, the intrinsic crystalline packing structure of Y6, currently the hallmark molecule among Y-series non-fullerene acceptors (NFAs), has not been unambiguously determined. Here, employing grazing-incidence wide-angle X-ray scattering (GIWAXS), we managed to uncover the intrinsic crystalline packing structure of Y6 in the BHJ active layer of OSCs, which is found to be different from its single-crystal structure reported previously. Moreover, we find that solvent additive 1-chloronaphthalene (CN) can induce highly ordered packing of Y6 in BHJ thin films. With the help of atomistic molecular dynamics simulations, it is revealed that π–π interactions generally exist between naphthalene derivatives and IC terminals of Y6 analogues, which would essentially improve their long-range ordering. Our work reveals the intrinsic crystalline packing structure of Y6 in the BHJ active layer as well as its crystallization mechanism in thin films, thus providing direct correlations between this crystalline packing and the device characteristics and photophysical properties. [ABSTRACT FROM AUTHOR]

The Suzuki–Miyaura cross‐coupling is one of the most important and powerful methods for constructing C−C bonds. However, the protodeboronation of arylboronic acids hinder the development of Suzuki–Miyaura coupling in the precise synthesis of conjugated polymers (CPs). Here, an anhydrous room temperature Suzuki–Miyaura cross‐coupling reaction between (hetero)aryl boronic esters and aryl sulfides was explored, of which universality was exemplified by thirty small molecules and twelve CPs. Meanwhile, the mechanistic studies involving with capturing four coordinated borate intermediate revealed the direct transmetalation of boronic esters in the absence of H2O suppressing the protodeboronation. Additionally, the room temperature reaction significantly reduced the homocoupling defects and enhanced the optoelectronic properties of the CPs. In all, this work provides a green protocol to synthesize alternating CPs. [ABSTRACT FROM AUTHOR]