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Alkali-salt and Lewis base are introduced into quasi-2D perovskite to modulate the phase distribution and serve as a passivating agent, respectively.

Ternary polymer solar cells were fabricated by introducing dithienocyclopentacarbazole (DTC) based non-fullerene acceptor DTTC-4ClC9 into PM6:BTP-BO-4Cl host blends, and the champion power conversion efficiency of 18.21% was achieved.

Crosslinkable organic semiconductors in optoelectronic devices have attracted extensive attention due to the outstanding advantages of strong solvent resistance and stable film morphology.

A pH-neutral aqueous anthraquinone-iron flow battery is demonstrated. The self-association of the anthraquinone is realized via noncovalent interactions.

Solvent polishing engineering is adopted to remove the relatively loose defect layer without damaging carrier injection in blue perovskite light-emitting-diodes (PeLEDs). Synchronously, the polishing effects depending on the solvents are discussed in detail. Finally, optimized blue PeLEDs were obtained with a maximum external quantum efficiency of 5.18%, high brightness of 3737 cd m

An anthraquinone derivative is developed to modify the SnO2 interface in organic solar cells via the multi-site coordination effect, yielding outstanding photovoltaic performances and device stability.

The narrow bandgap Pb-Sn hybrid perovskite materials with lower toxicities and adjustable optical bandgaps provide the opportunity to construct high-efficiency perovskite solar cells (PerSCs). To solve the issues of the uncontrollable crystallization rate of Pb-Sn perovskite and easy oxidation of Sn2+, a β-diketone-based additive, N,N,N',N'-tetraphenylmalondiamide (TPMA), is introduced to coordinate with Pb2+ and Sn2+. The introduction of TPMA can improve the morphology of perovskite films and decrease the density of defect states, resulting in an enhanced power conversion efficiency of >20% and improved stability. The PerSC without encapsulation retains 94% of its initial efficiency after being stored for 1000 h in a nitrogen-filled glovebox and shows a lifetime of only 8% degradation after being continuously heated for 100 h at 80 °C. This work represents a new strategy of introducing a β-diketone ligand as an additive in precursor engineering for achieving efficient and stable PerSCs.

Crystal growth of two-dimensional organic–inorganic hybrid perovskite has attracted much attention toward adjusting the orientation to obtain higher PCE and more lasting operational stability.

An electron collection layer (ECL) between a photoactive overlay and an electrode plays a crucial role in optimizing the light field and charge extraction in bulk-heterojunction (BHJ) polymer solar...

With advances in material science and a more in-depth understanding of device engineering, the power conversion efficiency (PCE) of solution-processed organic photovoltaic (OPV) cells have significantly boosted in the past few years. In 2019, a high PCE of 15.7% was achieved in the OPV cells adopting a wide bandgap polymer PM6 and a new emerging non-fullerene acceptor Y6. Such outstanding performance has attracted lots of research attention, driving considerable efforts to improve or take advantage of the high-performance PM6:Y6-based system. In this review, we first concentrate on the structural characteristics of PM6 and Y6 with the focus on understanding why their combination for OPV application can obtain such high efficiency. We also update the recent progress in highly efficient PM6:Y6-based OPV cells via various optimizing strategies. Then we summarize the other applications of the PM6:Y6-based system in semi-transparent, flexible or laye-by-layer devices. The prospects for future OPV studies will be suggested in the end.

The typical thickness of the photoactive layer in organic solar cells (OSCs) is around 100 nm, which limits the absorption efficiency of the incident light and the power conversion efficiency (PCE) of OSCs. Therefore, light-trapping schemes to reduce the optical losses in the thin photoactive layers are critically important for efficient OSCs. Herein, light-trapping and electron-collection dual-functional small organic molecules, N,N,N',N'-tetraphenyloxalamide (TPEA) and N,N,N',N'-tetraphenylmalonamide (TPMA), are designed and synthesized by a one-step acylation reaction. Driven by strong intermolecular force, TPEA and TPMA tend to self-aggregate into hemispherical light-trapping nanodots on the photoactive layer, resulting in enhanced light harvesting. Meanwhile, TPEA and TPMA demonstrate high electron mobility and excellent electron-collection ability. Compared with the device without cathode buffer layer (CBL, PCE = 14.09%), PM6:BTP-eC9 based OSCs with TPEA and TPMA light-trapping CBLs demonstrate greatly enhanced PCE of 16.21% and 17.85%, respectively. Furthermore, a record PCE of 19.02% can be achieved for PM6:BTP-eC9:PC

All-inorganic CsPbI

The integrated perovskite/organic solar cell (IPOSC) is widely concerned as an effective approach to broaden the spectrum of perovskite solar cell (PerSC) by utilizing near-infrared light of lower bandgap organic semiconductor. Compared to tandem solar cells, the IPOSCs eliminate the preparation of the intermediate layer and simplify the manufacturing process, but retain the advantages of wide light harvesting. Meanwhile, the IPOSCs can maintain the open-circuit voltage as high as PerSCs. This review summarizes the recent developments of perovskite materials and low-bandgap organic conjugated materials applied in solar cells. Then, the working mechanism of IPOSCs and the recent developments of IPOSCs based on low-bandgap donor and acceptor materials are highlighted. Besides, the study of charge dynamic in IPOSC is summarized. Finally, the potential of IPOSCs and approach to improve device performance are also envisaged.

Metal halide perovskite light-emitting diodes (PeLEDs) are a new type of electroluminescent device with wide application in flat-panel displays and solid-state lighting. The charge recombination at the electrode interfaces and within the emission layer are the key factors restricting the performance of PeLEDs. In this work, the charge transport layers on both sides of the perovskite are optimized simultaneously to reduce the energy loss at the interfaces. Solution-processed aluminum-doped zinc oxide (AZO) nanoparticles are introduced as the electron transport layer in the traditional device structure, which effectively simplifies the device manufacturing process and greatly improves the device performance. Furthermore, an ultra-thin polymethyl methacrylate (PMMA) layer is introduced as a tunneling layer to reduce the exciton quenching between the hole transport layer and the perovskite emission layer. Poly(2-ethyl-2-oxazoline) (PEOX) is used as an additive to significantly enhance the solvent resistance of the perovskite layer. By collaborative optimization, a deep red PeLED emitting at 683 nm with a turn-on voltage of only 1.6 V and a maximum brightness of 7798 cd m−2 is achieved, providing a new idea for the development of high-performance all-solution-processed PeLEDs.

Carbon dot (CD)-based room temperature phosphorescence (RTP) nanomaterials have constituted a research hotspot in multidisciplinary fields. Among the promising RTP CDs, fluorescence–phosphorescence dual emissive CDs (FP-CDs) are currently drawing enormous attention. Herein, highly efficient blue-green FP-CDs were easily prepared by a solvent-free pyrolysis treatment of hydroxyurea. The obtained FP-CDs showed high photoluminescence and phosphorescence quantum yields of 21% and 13%, respectively. Detailed experimental characterization revealed that the efficient dual-emission property is derived from the aromatic carbonyl groups at the edge of FP-CDs. Benefiting from the unique optical performance, FP-CDs exhibited good potential in anticounterfeiting and information encryption. This study offers a new strategy for developing dual-emission fluorescence–phosphorescence nanomaterials.

Combining wide bandgap and narrow bandgap organic materials to construct tandem organic solar cells (OSCs) offers opportunities for overcoming the efficiency limitation of single-junction OSCs. Com...

Facile synthesis of an interfacial layer in organic solar cells (OSCs) is important for broadening material designs and upscaling photovoltaic conversion efficiency (PCE). Herein, a mild solution process of spin-coating In(acac)3 and Ga(acac)3 isopropanol precursors followed by low-temperature thermal treatment was developed to fabricate In2O3 and Ga2O3 cathode buffer layers (CBLs). The introduction of In2O3 or Ga2O3 CBLs endows PM6:Y6-based OSCs with outstanding performance and high PCEs of 16.17% and 16.01%, respectively. Comparison studies present that the In2O3 layer possesses a work function (WF) of 4.58 eV, which is more favorable for the formation of ohmic contact compared with the Ga2O3 layer with a WF of 5.06 eV and leads to a higher open circuit voltage for the former devices. Electrochemical impedance spectroscopy was performed to reveal how In2O3 and Ga2O3 affect the internal charge transfer and the origin of their performance difference. Although In2O3 possesses lower series resistance loss, Ga2O3 has a higher recombination resistance, which enhances the device fill factor and compensates for its series resistance loss to some extent. Comparative analysis of the photo-physics of In2O3 and Ga2O3 suggests that both are excellent CBLs for highly efficient OSCs.

All-inorganic halide perovskite solar cells (PerSCs) have achieved rapid development in recent years. However, limited by narrow absorption bands, the power conversion efficiency (PCE) of all-inorganic halide PerSCs lag behind the organic-inorganic hybrid ones. In this contribution, to expand their absorption spectra and enhance the PCE, tandem solar cells (TSCs) with inorganic perovskite and organic conjugated molecules are constructed, utilizing CsPbI2Br as an ultraviolet-visible light absorber and a PTB7-Th:IEICO-4F bulk-heterojunction (BHJ) active layer as a near-infrared light absorber. To physically and electronically connect the front and rear subcells, P3HT/MoO3/Ag/PFN-Br is introduced as an interconnecting junction. Finally, the TSCs exhibit a remarkably higher PCE of 17.24% compared to that of the single junction PerSCs (12.09%) and organic solar cells (OSCs) (10.89%). These results indicate that the combination of all-inorganic perovskite and a low bandgap organic active layer for TSCs is a feasible approach to realize broad spectra utilization and efficiency enhancement.

The printable electrode interlayer with excellent thickness tolerance is crucial for mass production of organic solar cells (OSCs) by solution-based print techniques. Herein, high-quality printable SnO2 films are simply fabricated by spin-coating or blade-coating the chemical precipitated SnO2 colloid precursor with post thermal annealing treatment. The SnO2 films possess outstanding optical and electrical properties, especially extreme thickness-insensitivity. The interfacial electron trap density of SnO2 cathode interlayers (CILs) are very low and show negligible increase as the thicknesses increase from 10 to 160 nm, resulting in slight change of the power conversion efficiencies (PCEs) of the PM6:Y6 based OSCs from 16.10% to 13.07%. For blade-coated SnO2 CIL, the PCE remains high up to 12.08% even the thickness of SnO2 CIL is high up to 530 nm. More strikingly, the large-area OSCs of 100 mm2 with printed SnO2 CILs obtain a high efficiency of 12.74%. To the best of our knowledge, this work presents the first example for the high-performance and large-area OSCs with the thickness-insensitive SnO2 CIL.

The organic-inorganic halide perovskite solar cell (PerSC) is the state-of-the-art emerging photovoltaic technology. However, the environmental water/moisture and temperature-induced intrinsic degradation and phase transition of perovskite greatly retard the commercialization process. Herein, a dual-functional organic ligand, 4,7-bis((4-vinylbenzyl)oxy)-1,10-phenanthroline (namely, C1), with crosslinkable styrene side-chains and chelatable phenanthroline backbone, synthesized via a cost-effective Williamson reaction, is introduced for collaborative electrode interface and perovskite grain boundaries (GBs) engineering. C1 can chemically chelate with Sn

The development of new electron transporting layer (ETL) materials to improve the charge carrier extraction and collection ability between cathode and the active layer has been demonstrated to be an effective approach to enhance the photovoltaic performance of organic solar cells (OSCs). Herein, water-soluble carbon dots (CDs) as ETL material have been creatively synthesized by a vigorous chemical reaction between polyethylenimine (PEI) and 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) via a simple one-step hydrothermal method. Taking full advantage of the high electron transfer property of PTCDA and the work function (

Power conversion efficiencies (PCEs) and device stability are two key technical factors restricting the commercialization of organic solar cells (OSCs). In the past decades, though the PCEs of OSCs have been significantly enhanced, device instability, especially in the state-of-the-art nonfullerene system, still needs to be solved. In this work, an effective crosslinker (namely, DTODF-4F), with conjugated fluorene-based backbone and crosslinkable epoxy side-chains, has been designed and synthesized, which is introduced to enhance the morphological stabilization of the PM6:Y6-based film. This crosslinker with two epoxy groups can be in situ crosslinked into a stable network structure under ultraviolet radiation. We demonstrate that DTODF-4F, which acted as a third component, can promote the exciton dissociation rate and reduce traps/defects, finally resulting in the enhancement of efficiency. In particular, the OSC devices exhibit better stability under continuous heating owing to the morphology fixation of the bulk heterojunction. This work drives the development direction of morphological stabilization to further improve the performance and stability of OSCs.

Carbon quantum dots (CQDs) have developed into prospective nanomaterials for next-generation lighting and displays due to their intrinsic advantages of high stability, low cost, and environmental friendliness. However, confined by the spin-forbidden nature of triplet state transitions, the highest theoretical value of external quantum efficiency (EQE) of fluorescent CQDs is merely 5%, which fundamentally limits their further application in electroluminescent light-emitting diodes (LEDs). Soluble phosphorescent CQDs offer a means of breaking the shackle to achieve efficient monochromatic electroluminescence, especially red emission, which is a pivotal constituent in full-color displays. Here, the synthesis of red (625 nm) phosphorescent carbon quantum dot organic frameworks (CDOFs) with a quantum yield of up to 42.3% and realization of high-efficiency red phosphorescent electroluminescent LEDs are reported. The LEDs based on the CDOFs exhibited a red emission with a maximum luminance of 1818 cd m-2 and an EQE of 5.6%. This work explores the possibility of a new perspective for developing high-performance CQD-based electroluminescent LEDs.