Polarization detection enhances signal contrast and is widely utilized in diverse advanced applications. An ongoing challenge is the development of high-performance polarization-sensitive photodetectors based on optically anisotropic organic semiconductors, particularly in the near-infrared (NIR) region. While uniaxially aligned pi-conjugated polymers with high aspect ratios exhibit strong linear dichroism and have shown promise, their limited NIR performance and heavy reliance on polymer material now represent critical limitations. Here, a breakthrough is reported in achieving giant linear dichroism and exceptional polarization detection with low aspect-ratios (AR) non-fullerene small-molecule (NFSM) acceptors, extending polarization sensitivity from the UV-vis to the NIR range. An impressive dichroic ratio of 27.1 at 605 nm and 12.0 at 780 nm is demonstrated. The maximum polarization photocurrent ratio is 11.2 at 780 nm under parallel versus perpendicular polarized light. This unprecedented performance originates from synergistic molecular alignment, wherein NFSMs significantly enhance the uniaxial orientation of both the polymer matrix and the NFSMs themselves during self-assembly and thermal annealing. Besides, such a linear-polarization-sensitive photodetectors (LPS-PDs) are showcased in generating degree-of-linear-polarization imaging. The work establishes NFSMs as a viable material system for next-generation of organic LPS-PDs and provides fundamental insights into structural origins of polarization sensitivity in low AR organic semiconductors.

Carbazole-derived self-assembled monolayers (SAMs) are promising materials for hole-extraction layer (HEL) in conventional organic photovoltaics (OPVs). Here, a SAM Cbz-2Ph derived from 3,6-diphenylcarbazole is demonstrated. The large molecular dipole moment of Cbz-2Ph allows the modulation of electrode work function to facilitate hole extraction and maximize photovoltage, thus improving the OPV performance. Additionally, the flanking aryls of Cbz-2Ph help establish CH-pi interactions for forming a dense and well-organized SAM HEL and exhibit stronger van der Waals interactions with the donor PM6 than acceptor BTP-eC9. The stronger SAM-donor interactions modulate the PM6 distribution in PM6:BTP-eC9 bulk-heterojunction film, leading to PM6 enrichment near HEL to facilitate efficient hole extraction to the ITO anode in conventional p-i-n OPVs. Consequently, binary PM6:BTP-eC9-based devices incorporating the Cbz-2Ph HEL demonstrate an impressive efficiency of 19.18%. These cells also showcase excellent operational stability, with a T80 lifetime of approximate to 1260 h at the maximum power point, over 10 times longer than those using the traditional PEDOT:PSS HEL (T80 approximate to 96 h). Furthermore, the universal applicability of Cbz-2Ph as a HEL is evident through its successful implementation in PM6:BTP-eC9:L8-BO-F-based ternary devices and PM6:BTP-eC9-based printed OPV devices, achieving a PCE of 19.30% and 16.96%, respectively.

Circularly polarized (CP) light is extensively used in various fields such as asymmetrical synthesis, sensing, and advanced displays. Consequently, significant efforts have been made to develop chiral materials that intrinsically emit CP light with a large dissymmetry factor (g-factor). It is widely considered that the dissymmetry factor for individual organic emitters, due to the amplitude offset between their electric and magnetic transition dipole moments, is limited to approximate to 10(-2), which is inadequate for practical applications. Recent efforts to enhance CP light emission have therefore focused on amplifying the dissymmetry of circularly polarized luminescence (CPL), often via specific energy transfer processes. Here, a fundamental mechanism is discovered - excited-state hybridization, which amplifies CPL through excitonic coupling without relying on energy transfer processes. Through this wavefunction hybridization, both the amplitude and sign of the rotatory strength related to the molecular emitter's electronic transition are modified to align with its chiral environment, remarkably boosting the CP luminescence from an intrinsic dissymmetry factor of -10(-3) up to +0.40. This breakthrough allows for more versatile design strategies for chiral emissive systems, moving beyond designs limited to energy transfer processes and paving the way for new approaches to achieve strong CP emissive materials.

The incorporation of thick active layers (>300 nm) is an essential requirement for wide-scale industrial production of organic solar cells (OSCs). However, it is still challenging to achieve efficient thick film devices, in particular for all-polymer OSCs, which are generally considered the most stable type of OSCs. In this study, a simple yet effective method is introduced by using a direct current (DC) field to manipulate the morphology of bulk heterojunction (BHJ) films within all-polymer OSCs during a blade coating process. By utilizing this method, a favorable vertical phase distribution is achieved, thereby effectively reducing the electron percolation threshold and enhancing the overall device performance. With this, an outstanding efficiency of 17.59% is achieved for thick-film all-polymer devices by blade-coating, which is the best performance in this category. This study introduces a non-contact DC field method aimed at mitigating the fabrication challenges encountered when transitioning thick-film all-polymer systems from laboratory to manufacturing settings, and will potentially contributing to the advancement of the OSC industrialization.

Although all-polymer solar cells (All-PSCs) have attached increasing attention for their remarkable stability advantages, their photovoltaic performance significantly lags behind organic solar cells based on small molecule acceptors. This is primarily due to their limited entropy increase in the active layer and poor compatibility between polymer donors and acceptors, leading to excessive phase separation. To address this limitation, two novel copolymer donors, PBDTF-ttTPD and PBDTSi-ttTPD, are designed and synthesized, which are explored by polymerizing fluorine-modified benzodithiophene (BDT) and alkylsilyl-functionalized BDT units with thieno[3,4-c]pyrrole-4,6(5H)-dione (TPD) unit, respectively. Both the two TPD-copolymers demonstrate comparable energy levels and optical absorption properties, while the incorporating of alkylsilyl groups in PBDTSi-ttTPD improves solubility, lowers electrostatic potential (ESP), and facilitates optimal molecular stacking. Consequently, the blend film of PBDTSi-ttTPD:PY-IT achieves an optimal interpenetrating network, reducing phase separation and significantly improving miscibility compared to PBDTF-ttTPD:PY-IT blends. This morphological evolution significantly boosts device performance, including extended carrier lifetime, improved charge transport, and minimized energy disorder. Ultimately, these advancements resulted in a substantial increase in power conversion efficiency, from 13.93% to 18.03%. Furthermore, the relationship between polymer donors/acceptors miscibility and energy loss are deeply explored, providing insights for future optimizations.

Printing of large-area solar panels necessitates advanced organic solar cells with thick active layers. However, increasing the active layer thickness typically leads to a marked drop in the power conversion efficiency. Here we developed an organic semiconductor regulator, called AT-beta 2O, to tune the crystallization sequence of the components in active layers. When adding AT-beta 2O in the donor (D18-Cl) and acceptor (N3) blend, N3 crystallizes behind D18-Cl, and this phenomenon is different from the co-crystallization observed in binary D18-Cl:N3 blends. This manipulation of crystallization dynamics is favourable to form bulk-heterojunction-gradient vertical phase separation in the active layer accompanied by the high crystallinity of the acceptor and balanced charge carrier mobilities in thick films. The resultant single-junction organic solar cells exhibited a certified power conversion efficiency of over 20%, as well as demonstrated exceptional adaptability across the active layer thicknesses (100-400 nm) and remarkable universality. Such breakthroughs enable large-area modules with a certified power conversion efficiency of 18.04%.

Molecular weight optimization is crucial for high-performance stretchable conjugated polymer films. However, an in-depth understanding of molecular weight distribution on solution assembly, film microstructures, and electrical/mechanical properties of conjugated polymers is lacking. Herein, a model conjugated polymer, poly(indacenodithiophene-co-benzothiadiazole) (IDTBT), with a similar weight-average molecular weight but different polydispersity indexes (PDIs) of 3.2, 2.4, and 1.6 is investigated. The low-PDI polymer, containing a high content of homogeneous long chains, facilitates sufficient interchain aggregation caused by the enhanced chain entanglement and prolonged aggregation dynamics, which creates a low-crystallinity film containing long-chain well-connected aggregates and chain entanglement networks. Consequently, the charge mobility increases from 2.1 to 3.1 cm2 V-1 s-1 as PDI decreases from 3.2 to 1.6. During stretching, the polymer chains align more effectively along the strain direction in the low-PDI film, which creates more dynamic sliding sites and short-range aggregates to dissipate the strain energy. Thus, the low-PDI polymer film exhibits a high charge mobility of 1.0 +/- 0.1 cm2 V-1 s-1 at 100% strain and 0.9 +/- 0.1 cm2 V-1 s-1 after 100 cycles of stretching-releasing at 25% strain, which significantly outperforms the high-PDI film. This work demonstrates the significance of polydispersity optimization for developing mechanically robust polymer semiconductor films in stretchable electronics.

The poor intrinsic perovskite absorber stability is arguably a central limitation challenging the prospect of commercialization for photovoltaic (PV) applications. Understanding the nanoscopic structural features that trigger instabilities in perovskite materials is essential to mitigate device degradation. Using nanostructure characterization techniques, we observe the local degradation to be initiated by material loss at stacking faults, forming inherently in the (011)-faceted perovskite domains in different formamidinium lead triiodide perovskite compositions. We introduce Ethylene Thiourea (ETU) as an additive into the perovskite precursor, which manipulates the perovskite crystal growth and results in dominantly in-and out-of-plane (001) oriented perovskite domains. Combining in-depth experimental analysis and density functional theory calculations, we find that ETU lowered the perovskite formation energy, readily enabling crystallization of the perovskite phase at room temperature without the need for an antisolvent quenching step. This facilitated the fabrication of high-quality large area 5 cm by 5 cm blade-coated perovskite films and devices. Encapsulated and unmasked ETU-treated devices, with an active area of 0.2 cm(2), retained > 93 % of their initial power conversion efficiency (PCE) for > 2100 hours at room temperature, and additionally, 1 cm(2) ETU-treated devices maintained T80 (the duration for the PCE to decay to 80 % of the initial value) for > 600 hours at 65 degrees C, under continuous 1-sun illumination at the maximum power point in ambient conditions. Our demonstration of scalable and stable perovskite solar cells represents a promising step towards achieving a reliable perovskite PV technology.

Organic solar cells (OSCs) have achieved power conversion efficiencies (PCEs) of >20%, although almost all top-performance devices having a thin active layer of approximate to 100 nm and are being processed with environmentally harmful halogenated solvents/additives. However, attempting to fabricate OSCs with thick active layers from non-halogenated solvents/additives normally leads to dramatically decreased PCEs, seriously restricting their industrialization. To overcome the above shortcomings, it is developed an all-hydrocarbon-based system combined with toluene solvent and fluorene (DBP) solid additive to process active layer (PM6:L8-BO) thickness-insensitive efficient OSCs. Owing to DBP having good planarity, excellent volatility, and stronger interaction with L8-BO, its treated active layers exhibit ordered molecular packing, suitable phase separation, and enhanced charge transport, resulting in a superior PCE of 18.64%. Notably, using D18:BTP-eC9 as the active layer, the OSCs achieve a record-high PCE of 19.61% among the all-hydrocarbon-based system processed devices. Due to the increased crystallinity and optimized hierarchical morphology, the above OSCs show high thickness-tolerance and provide an excellent PCE of approximate to 18% with a 300 nm active layer, ranking among the highest PCEs for the all-hydrocarbon-based system processed thick-film devices. This work develop an all-hydrocarbon-based system to process active layers in an environmentally friendly way for thickness-insensitive OSCs, with record-high PCEs, toward future industrial production.

The key factor restricting the power conversion efficiency (PCE) of organic solar cells (OSCs) is the energy loss (Eloss), which is the difference between the optical bandgap (Eg) of the active layer and open-circuit voltage (VOC) of the device. To achieve lower Eloss, it is necessary to obtain an appropriate donor-acceptor phase separation size to accelerate exciton dissociation and inhibit the recombination process. However, in most high-efficiency non-fullerene systems, acceptors often exhibit excessive aggregation phenomena. The decrease in the interface area leads to a decrease in exciton dissociation efficiency, which increases the energy loss. Herein, we report a ternary strategy to decrease the crystallization time of the acceptor and inhibit the excessive aggregation condition of a non-fullerene acceptor. We chose a donor poly{[4,8-bis[5-(2-ethylhexyl)-4-fluoro-2-thienyl]benzo[1,2-b:4,5-b ']-dithiophene-2,6-diyl]-alt-[2,5-thiophenediyl[5,7-bis(2-ethylhexyl)-4,8-dioxo-4H,8H-benzo[1,2-c:4,5-c ']dithiophene-1,3-diyl]]} (PM6) and a non-fullerene acceptor (2,2 '-((2Z,2 ' Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2 '',3 '':4 ',5 ']thieno[2 ',3 ':4,5]pyrrolo[3,2-g]thieno[2 ',3 ':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile) (Y6) as the model system. Y6 is prone to forming a tightly packed structure due to its planar curved skeleton. To suppress the excessive aggregation, we chose poly[2,2 '-((2Z,2 ' Z)-((12,13-bis(2-octyldodecyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2 '',3 '':4 ',5 ']thieno[2 ',3 ':4,5]pyrrolo[3,2-g]thieno[2 ',3 ':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile-co-2,5-thiophene] (PY-IT) as a second acceptor, which has good compatibility with Y6. By using in situ UV-visible absorption spectroscopy to monitor the film formation kinetics of Y6, it was found that after adding 15 wt% PYIT, the total crystallization time of Y6 decreased and the excessive aggregation of Y6 was inhibited. In the PM6:Y6 system, Y6 only had one crystallization and film-forming process. While in the PM6:Y6+15 wt% PYIT system, the process of film formation became more complex, with two stages of aggregation. PYIT crystallized before Y6, when Y6 began to crystallize, PYIT has occupied a portion of the crystallization growth space. What is more, PYIT delayed the crystallization process of Y6, and the change in the acceptor peak position showed a stable region. After that, Y6 began to aggregate and the crystallization time of Y6 was shorter than that of the binary system. As a result, PYIT alleviated the excessive aggregation of Y6, resulting in better mixing between the non-fullerene acceptor and the donor, increasing the interface area and enabling faster dissociation of excitons. In addition, the vertical phase separation of the active layer has also been optimized, allowing more donors enriched near the anode, enhancing the efficiency of charge extraction. The improved morphology of the active layer results in a better interface area, which can not only ensure exciton dissociation and charge generation, but also reduce the transfer time, which is conducive to reducing energy loss. As a result, Eloss reduced from 0.559 eV to 0. 539 eV, and the optimized ternary OSC exhibited a PCE of 17.05%. PYIT was added to the PM6:Y6 system to delay and shorten the crystallization time of Y6. The ternary strategy has been successfully proven to increase the D/A interface area for faster exciton dissociation. The Eloss decreased (0.559 eV to 0.539 eV), and the PCE increased (15.40% to 17.05%).