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Coulomb interactions play a crucial role in low-dimensional semiconductor materials, e.g., 2D layered semiconductors, dictating their electronic and optical properties. However, fundamental questions remain as to whether and how Coulomb interactions affect the charge or energy flow in 2D heterostructures, which is essential for their light-electricity conversions. Herein, using ultrafast spectroscopy, we report real space coupled electron-hole dynamics in 2D heterostructures. We show in (WSe

van der Waals heterostructures combining perovskites of strong light absorption with atomically thin two-dimensional (2D) transition-metal dichalcogenides (TMDs) hold great potential for light-harvesting and optoelectronic applications. However, current research studies integrating TMDs with low-dimensional perovskite nanomaterials generally suffer from poor carrier/energy transport and harnessing, stemming from poor interfacial interaction due to the nanostructured nature and ligands on surface/interface. To overcome the limitations, here, we report prototypical three-dimensional (3D)/2D perovskite/TMD heterostructures by combing highly smooth and ligand-free CsPbBr3 film with a WSe2 monolayer. We show that the energy transfer at interface occurs through asymmetric two-step charge-transfer process, with ultrafast hole transfer in ∼200 fs and subsequent electron transfer in ∼10 ps, driven by the asymmetric type I band alignment. The energy migration and transfer from CsPbBr3 film to WSe2 can be well described by a one-dimensional diffusion model with a carrier diffusion length of ∼500 nm in CsPbBr3 film. Thanks to the long-range carrier migration and ultrafast interfacial transfer, highly efficient (>90%) energy transfer to WSe2 can be achieved with CsPbBr3 film as thick as ∼180 nm, which can capture most of the light above its band gap. The efficient light and energy harvesting in perovskite/TMD 3D/2D heterostructures suggest great promise in optoelectronic and photonic devices.

The field of organic solar cells has experienced paradigm-shifting changes in recent years because of the emergence of nonfullerene acceptors (NFAs). It is critically important to gain more insight...

Currently, high-performance organic solar cells (OSCs) are mainly composed of narrow band gap (NBG) nonfullerene acceptors and medium band gap (MBG) polymer donors, whereas the solar cells based on...

It is widely known that the miscibility between donor and acceptor is a crucial factor that affects the morphology and thus device performance of nonfullerene organic solar cells (OSCs). In this Letter, we show that incorporating a third component with lower miscibility and higher lowest unoccupied molecular orbital (LUMO) level into the state-of-the-art PM6:Y6 system can significantly enhance the performance of devices. The best results of the ternary devices are achieved by adding a small molecular acceptor named ITCPTC (similar to 5% w/w), which significantly improves the power conversion efficiency (PCE) of the host system from 16.44% to 17.42%. The higher LUMO of the third component increases the open-circuit voltage (V-oc), while the low miscibility enlarges the domains and leads to improved short-circuit current density (J(sc)) and fill factor (FF). The efficacy of this strategy is supported by using other nonfullerene third components including an asymmetric small molecule (N7IT) and a polymer acceptor (PF2-DTC), which play the same role as ITCPTC and boost the PCEs to 16.96% and 17.04%, respectively. Our approach can be potentially applied to a wide range of OSC material systems and should facilitate the development of the OSC field.

Here we demonstrate efficient all-polymer solar cells (all-PSCs) based on a polymer acceptor named PFBDT-IDTIC. By combining PFBDT-IDTIC with a fluorinated donor polymer (PM6), a high power conversion efficiency of 10.3% can be achieved, which is the highest value reported to date for single-junction all-PSCs. This performance can be attributed to its good absorption property (absorption coefficient: 2.74 × 105 cm–1) and high electron mobility of PFBDT-IDTIC. It is also found that the choice of donor polymer has major impacts on the performance of the cell. By replacing PBDB-T with its fluorinated counterpart, PM6, the VOC, JSC, and FF of the devices were all improved, which can be attributed to the deeper HOMO level of PM6 and more crystalline and pure domains of the active layer blends. Our study provides a promising polymer acceptor for all-PSCs and also shows that selecting a matching donor polymer is important in achieving the optimal all-PSC performance.

Three selenophene-incorporated quaterchalcogenophene-based donor–acceptor copolymers PFBT2Th2Se, PFBT2Se2Th, and PFBT4Se are designed and synthesized. To systematically fine-tune the molecular properties and investigate the chalcogen effect, PFBT2Th2Se and PFBT2Se2Th hybridize two thiophenes and two selenophenes as the donor with different isomeric main-chain placement while thiophene-free PFBT4Se uses quaterselenophene as the donor. On account of the selenophene’s advantageous features such as higher quinoidal population and higher molecular polarizability, the three polymers show good light-harvesting ability, strong intermolecular interactions, high crystallinity, and high charge mobilities. Bulk-heterojunction solar cells incorporating these selenophene-containing polymers have exhibited promising photovoltaic performance with impressive current densities over 20 mA/cm2. The device with the PFBT2Se2Th:PC71BM blend showed a PCE of 9.02% with a Jsc of 21.02 mA/cm2. In addition, the device using quaterse...

[reaction: see text] Two methods have been developed for the synthesis of epoxide 36. The first uses (+)-pulegone 25 as an enantiopure starting material and introduces the requisite intricacy of target 22 in 12 operations. The second method employs an enantiospecific catalytic Jacobsen epoxidation of 1a and is five operations shorter. The second sequence features an oxygen-directed alkylative oxidation reaction that re-establishes the dienyl sulfone functionality with concomitant 1,3-transposition of the sulfone moiety.

Treatment of TpRuCl(PPh3)(CH3CN) (Tp = hydrotris(pyrazolyl)borate) with NaBH4 in ethanol did not yield the expected hydride complex TpRuH(PPh3)(CH3CN) (2) but rather the methyl carbonyl complex TpRu(CH3)(CO)(PPh3) (1b). Formation of 1b was due to decarbonylation of ethanol by 2 generated in situ by NaBH4 reduction of TpRuCl(PPh3)(CH3CN). Analogous reactions in the presence of other primary alcohols RCH2OH (R = H, C2H5, n-C3H7, C6H5, C6H4CH3-4, and C6H4Cl-4) led to the corresponding σ-organyl complexes TpRuR(CO)(PPh3). A common feature of the reactions is that the R groups of alcohols RCH2OH become the σ-organyl groups in the final metal complexes. A mechanism involving metal−η2-aldehyde and −η2-dihydrogen intermediates is proposed for the decarbonylation reaction. This is supported by the observation of the η2-dihydrogen complex TpRuH(H2)(PPh3) (3) during the decarbonylation reaction. 3 was synthesized independently by heating a THF solution of 2 under 40 atm of H2 at 60 °C for 48 h or by heating 2 in CH3...

A series of new hydrotris(1-pyrazolyl)borate complexes of ruthenium were synthesized. Reaction of RuCl(HB(pz)3)(PPh3)2 with NaBH4 in ethanol produced the yellow monohydride complex RuH(HB(pz)3)(PPh3)2. Protonation of the monohydride complex RuH(HB(pz)3)(PPh3)2 with HBF4·Et2O in dichloromethane gave the molecular dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4. Reactions of the dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 with L (L = CH3CN, H2O, N2) produced the adducts [Ru(HB(pz)3)(PPh3)2(L)]BF4. The dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 could be regenerated by reactions of [Ru(HB(pz)3)(PPh3)2(L)]BF4 (L = CH3CN, H2O) with pressurized H2. Deprotonation of the molecular dihydrogen complex [Ru(HB(pz)3)(PPh3)2(H2)]BF4 occurred with NEt3 or H2O under hydrogen pressure. Treatment of RuCl(HB(pz)3)(PPh3)2 with LiBF4 in acetonitrile produced the bis-solvento complex [Ru(HB(pz)3)(PPh3)(CH3CN)2]BF4. Heating a THF/CH3CN (9/1) solution of RuCl(HB(pz)3)(PPh3)2 at 60 °C led to the formation of RuCl(HB(pz)3)(PP...

Protonation of CpFeH(P-P) (P-P = dppe, dppp) with HBF4 produced the molecular dihydrogen complexes [CpFe(H2)(P-P)]BF4. Protonation of CpOsH(P-P) (P-P = dppm, dppe, dppp) with HBF4 at −78 °C gave a mixture of cis-[CpOsH2(P-P)]BF4 and trans-[CpOsH2(P-P)]BF4. Depending on the size of the chelating rings, the thermodynamically stable structures of the protonated products at room temperature may be exclusively trans-[CpOsH2(P-P)]BF4 or a mixture of cis-[CpOsH2(P-P)]BF4 and trans-[CpOsH2(P-P)]BF4. At room temperature in dichloromethane solutions, [CpOsH2(dppm)]BF4 exists as a mixture of cis and trans isomers in a ratio of 10:1, [CpOsH2(dppe)]BF4 exists as a mixture of cis and trans isomers in a ratio of 1:70, and [CpOsH2(dppp)]BF4 adopts only trans geometry.

The cationic ruthenium−alkylidene complex [(PCy3)2(CO)(Cl)RuCHCHC(CH3)2]+BF4- (1) was found to catalyze both hydrovinylation and [2+2] cycloaddition reactions of alkynes and alkenes. The reaction of R‘C⋮CR‘ ‘ (R‘ = H, Ph, n-Pr; R‘ ‘ = Ph, n-Pr, p-Tol, SiEt3, CH2CH2OH) with ethylene in the presence of 1 (3 mol %) produced the hydrovinylation products 2 and 3. The analogous reaction of dimethyl acetylenedicarboxylate (R‘ = R‘ ‘ = CO2Me) with ethylene and norbornene resulted in the formation of the [2+2] cycloaddition products 4. Based on the experimental evidence, a plausible mechanism of the hydrovinylation reaction has been proposed via a sequential insertion of alkyne and ethylene to the hydride complex 7.