Solid Additive Engineering for Next-generation Organic Photovoltaics.

Solution-processed bulk heterojunction (BHJ) organic solar cells (OSCs) have emerged as a promising next-generation photovoltaic technology. In this emerging field, there is a growing trend of employing solid additives (SAs) to fine-tune the BHJ morphology and unlock the full potential of OSCs. SA engineering offers several significant benefits for commercialization, including the ability to i) control film-forming kinetics to expedite high-throughput fabrication, ii) leverage weak noncovalent interactions between SA and BHJ materials to enhance the efficiency and stability of OSCs, and iii) simplify procedures to facilitate cost-effective production and scaling-up.

Polymer Fiber Rigid Network with High Glass Transition Temperature Reinforces Stability of Organic Photovoltaics.

Organic photovoltaics (OPVs) need to overcome limitations such as insufficient thermal stability to be commercialized. The reported approaches to improve stability either rely on the development of new materials or on tailoring the donor/acceptor morphology, however, exhibiting limited applicability. Therefore, it is timely to develop an easy method to enhance thermal stability without having to develop new donor/acceptor materials or donor-acceptor compatibilizers, or by introducing another third component.

Rational molecular and device design enables organic solar cells approaching 20% efficiency.

For organic solar cells to be competitive, the light-absorbing molecules should simultaneously satisfy multiple key requirements, including weak-absorption charge transfer state, high dielectric constant, suitable surface energy, proper crystallinity, etc. However, the systematic design rule in molecules to achieve the abovementioned goals is rarely studied. In this work, guided by theoretical calculation, we present a rational design of non-fullerene acceptor o-BTP-eC9, with distinct photoelectric properties compared to benchmark BTP-eC9.

Stabilizing Top Interface by Molecular Locking Strategy with Polydentate Chelating Biomaterials toward Efficient and Stable Perovskite Solar Cells in Ambient Air.

The instability of top interface induced by interfacial defects and residual tensile strain hinders the realization of long-term stable n-i-p regular perovskite solar cells (PSCs). Herein, one molecular locking strategy is reported to stabilize top interface by adopting polydentate ligand green biomaterial 2-deoxy-2,2-difluoro-d-erythro-pentafuranous-1-ulose-3,5-dibenzoate (DDPUD) to manipulate the surface and grain boundaries of perovskite films. Both experimental and theoretical evidence collectively uncover that the uncoordinated Pb ions, halide vacancy, and/or I─Pb antisite defects can be effectively healed and locked by firm chemical anchoring on the surface of perovskite films.

Polydentate Ligand Reinforced Chelating to Stabilize Buried Interface toward High-Performance Perovskite Solar Cells.

The instability of the buried interface poses a serious challenge for commercializing perovskite photovoltaic technology. Herein, we report a polydentate ligand reinforced chelating strategy to strengthen the stability of buried interface by managing interfacial defects and stress. The bis(2,2,2-trifluoroethyl) (methoxycarbonylmethyl)phosphonate (BTP) is employed to manipulate the buried interface.

Advances in chloride additives for high-efficiency perovskite solar cells: multiple points of view.

Chloride (Cl) additives are rather effective in improving the performance of perovskite solar cells (PSCs) through the modulation of crystallization process and surface morphology. After incorporating Cl-containing additives, the optoelectrical properties of perovskite films, such as the electron/hole diffusion length and carrier lifetime, are greatly enhanced. However, only a trace amount of Cl has been identified in the resultant perovskite film, and the mechanism of efficiency improvement induced by Cl remains unclear.

Electronic Configuration Tuning of Centrally Extended Non-Fullerene Acceptors Enabling Organic Solar Cells with Efficiency Approaching 19 .

In the molecular optimizations of non-fullerene acceptors (NFAs), extending the central core can tune the energy levels, reduce nonradiative energy loss, enhance the intramolecular (donor-acceptor and acceptor-acceptor) packing, facilitate the charge transport, and improve device performance. In this study, a new strategy was employed to synthesize acceptors featuring conjugation-extended electron-deficient cores. Among these, the acceptor CH-BBQ, embedded with benzobisthiadiazole, exhibited an optimal fibrillar network morphology, enhanced crystallinity, and improved charge generation/transport in blend films, leading to a power conversion efficiency of 18.

Balancing the Efficiency and Synthetic Accessibility of Organic Solar Cells with Isomeric Acceptor Engineering.

With the continuous development of organic semiconductor materials and on-going improvement of device technology, the power conversion efficiencies (PCEs) of organic solar cells (OSCs) have surpassed the threshold of 19%. Now, the low production cost of organic photovoltaic materials and devices have become an imperative demand for its practical application and future commercialization. Herein, the feasibility of simplified synthesis for cost-effective small-molecule acceptors via end-cap isomeric engineering is demonstrated, and two constitutional isomers, BTP-m-4Cl and BTP-o-4Cl, are synthesized and compared in parallel.

Low-Temperature Solution Synthesis of Stable CsCuBr Single Crystals for Visible Light Communications.

Inorganic perovskites CsPbX (X = Cl, Br, I) have shown great potential as luminescent materials for a wide range of photoelectric devices. However, the practical use of these materials is limited due to the toxicity of lead and poor stability. Here, we present a facile low-temperature, solution-based method to synthesize lead-free and highly stable CsCuBr single crystals (SCs) without the use of organic solvents.

Solvent-Free Grinding Synthesis of Hybrid Copper Halides for White Light Emission.

Lead-free metal halides (LMHs) have recently attracted numerous attention in solid-state lighting due to their unique structures and outstanding optoelectronic properties. However, conventional preparation processes with the utilization of toxic organic solvents and high temperatures seem to impede commercial applications of LMHs. In this work, we successfully synthesize Cu-based metal halides (TMA)CuBrCl (TMA: tetramethylammonium) with high photoluminescence quantum yields (PLQYs) a solvent-free mechanical grinding method.

19.31% binary organic solar cell and low non-radiative recombination enabled by non-monotonic intermediate state transition.

Non-fullerene acceptors based organic solar cells represent the frontier of the field, owing to both the materials and morphology manipulation innovations. Non-radiative recombination loss suppression and performance boosting are in the center of organic solar cell research. Here, we developed a non-monotonic intermediate state manipulation strategy for state-of-the-art organic solar cells by employing 1,3,5-trichlorobenzene as crystallization regulator, which optimizes the film crystallization process, regulates the self-organization of bulk-heterojunction in a non-monotonic manner, i.

Application of Natural Molecules in Efficient and Stable Perovskite Solar Cells.

Perovskite solar cells (PSCs), one of the most promising photovoltaic technologies, have been widely studied due to their high power conversion efficiency (PCE), low cost, and solution processability. The architecture of PSCs determines that high PCE and stability are highly dependent on each layer and the related interface, where nonradiative recombination occurs. Conventional synthetic chemical materials as modifiers have disadvantages of being toxic and costly.

1-Adamantanamine Hydrochloride Resists Environmental Corrosion to Obtain Highly Efficient and Stable Perovskite Solar Cells.

Passivating the defective surface of perovskite film is a promising strategy to improve the stability and efficiency of perovskite solar cells (PSCs). Herein, 1-adamantanamine hydrochloride (ATH) is introduced to the upper surface of the perovskite film to heal the defects of the perovskite surface. The best-performance ATH-modified device has a higher efficiency (23.

Architecturally simple organic photodiodes with highly competitive figures of merit a facile self-assembly strategy.

Photodetectors (PDs) based on organic materials exhibit potential advantages such as low-temperature processing, and superior mechanical properties and form factors. They have seen rapid strides toward achieving performance metrics comparable to inorganic counterparts. Here, a simplified device architecture is employed to realize stable and high-performance organic PDs (OPDs) while further easing the device fabrication process.

Highly efficient copper-based halide single crystals with violet emission for visible light communication.

KCuBr single crystals (SCs) are synthesized using a cooling-induced crystallization method with violet emission due to self-trapped excitons (STEs) under photoexcitation. The prepared KCuBr SCs exhibit a high photoluminescence quantum yield (PLQY, 79.2%) and excellent stability against moisture, heat and UV light.

Flexible perovskite scintillators and detectors for X-ray detection.

X-ray detection and imaging technology has been rapidly developed for various fields since 1895, offering great opportunities to scientific and industrial communities. Particularly, flexible X-ray detectors have drawn numerous attention in medical-related applications, solving the uniform issues of traditional rigid X-ray detectors. Out of all the potential materials, metal halide perovskites (MHPs) have been emerged as excellent candidates as flexible X-ray scintillators and detectors owing to the advantages including low temperature solution processable, strong X-ray absorption coefficient, large mobility lifetime product and tunable bandgap.

Printable high-efficiency organic ionic photovoltaic materials discovered by high-throughput first-principle calculations.

Printable solar cells are promising for low cost and large-scale production. As the two main classes of printable solar cells, organic and perovskite solar cells show distinct advantages and apparent drawbacks. The latter stand as major obstacle toward their commercialization.

Flexible and stable copper-based halide scintillator for high-performance X-ray imaging.

RbCuBr nanocrystals with a high photoluminescence quantum yield (PLQY) of 75% were synthesized and then further mixed with polymethyl methacrylate to form flexible scintillators. The scintillators maintain a high PLQY, even after bending for 2000 cycles and storing in air for 28 days. X-Ray imaging of targeted objects was demonstrated based on the flexible scintillators, which exhibits a detection limit of 63 nGy s and a spatial resolution of 27.

Semiconducting Copolymers with Naphthalene Imide/Amide π-Conjugated Units: Synthesis, Crystallography, and Systematic Structure-Property-Mobility Correlations.

In a series of n-type semiconducting naphthalene tetracarboxydiimide (NDI)-dithiophene (T2) copolymers, structural and electronic properties trends are systematically evaluated as the number of NDI carbonyl groups is reduced from 4 in NDI to 3 in NBL (1-amino-4,5-8-naphthalene-tricarboxylic acid-1,8-lactam-4,5-imide) to 2 in NBA (naphthalene-bis(4,8-diamino-1,5-dicarboxyl)-amide). As the NDI-T2 backbone torsional angle falls the LUMO energy rises. However, the thienyl attachment regiochemistry also plays an important role in less symmetric NBL and NBA.

Symmetrically Fluorinated Benzo[1,2-:4,5-']dithiophene-Cored Donor for High-Performance All-Small-Molecule Organic Solar Cells with Improved Active Layer Morphology and Crystallinity.

Side-chain engineering is an efficient molecular design strategy for morphology optimization and performance improvement of organic solar cells (OSCs). Herein, a novel small-molecule donor C-2F, which owns a benzo[1,2-:4,5-']dithiophene (BDT) central unit with a symmetrically difluorinated benzene ring as a conjugated side chain, has been synthesized. The conjugated side chain possesses both the symmetry and halogenation effect in novel small molecular donor material.

Volatile Solid Additive-Assisted Sequential Deposition Enables 18.42% Efficiency in Organic Solar Cells.

Morphology optimization of active layer plays a critical role in improving the performance of organic solar cells (OSCs). In this work, a volatile solid additive-assisted sequential deposition (SD) strategy is reported to regulate the molecular order and phase separation in solid state. The OSC adopts polymer donor D18-Cl and acceptor N3 as active layer, as well as 1,4-diiodobenzene (DIB) as volatile additive.

Hybrid Cathode Interlayer Enables 17.4% Efficiency Binary Organic Solar Cells.

With the emergence of fused ring electron acceptors, the power conversion efficiency of organic solar cells reached 19%. In comparison with the electron donor and acceptor materials progress, the development of cathode interlayers lags. As a result, charge extraction barriers, interfacial trap states, and significant transport resistance may be induced due to the unfavorable cathode interlayer, limiting the device performances.

Correlating Electronic Structure and Device Physics with Mixing Region Morphology in High-Efficiency Organic Solar Cells.

The donor/acceptor interaction in non-fullerene organic photovoltaics leads to the mixing domain that dictates the morphology and electronic structure of the blended thin film. Initiative effort is paid to understand how these domain properties affect the device performances on high-efficiency PM6:Y6 blends. Different fullerenes acceptors are used to manipulate the feature of mixing domain.

Simultaneous Interfacial Modification and Crystallization Control by Biguanide Hydrochloride for Stable Perovskite Solar Cells with PCE of 24.4.

Interfacial modification, which serves multiple roles, is vital for the fabrication of efficient and stable perovskite solar cells. Here, a multifunctional interfacial material, biguanide hydrochloride (BGCl), is introduced between tin oxide (SnO ) and perovskite to enhance electron extraction, as well as the crystal growth of the perovskite. The BGCl can chemically link to the SnO through Lewis coordination/electrostatic coupling and help to anchor the PbI .

Artificial Intelligence Designer for Highly-Efficient Organic Photovoltaic Materials.

Designing efficient organic photovoltaic (OPV) materials purposefully is still challenging and time-consuming. It is of paramount importance in material development to identify basic functional units that play the key roles in material performance and subsequently establish the substructure-property relationship. Herein, we describe an automatic design framework based on an in-house designed La FREMD Fingerprint and machine learning (ML) algorithms for highly efficient OPV donor molecules.