Shou-Feng Zhang

Molecule-electrode interfaces play a pivotal role in defining the electron transport properties of molecular electronic devices. While extensive research has concentrated on optimizing molecule-electrode coupling (MEC) involving electrode materials and molecular anchoring groups, the role of the molecular backbone structure in modulating MEC is equally vital. Additionally, it is known that the incorporation of heteroatoms into the molecular backbone notably influences factors such as energy levels and conductive characteristics. In this work, we report a series of molecular wires that are organized in donor-acceptor-donor configurations, with distinct chalcogen substitutions, including oxygen (BOD), sulfur (BTD), and selenium (BSD). We investigated the electron transport properties using the scanning tunneling microscope break junction (STM-BJ) technique. Our results revealed that both the single-molecule conductance and the junction evolution feature are impacted by the heteroatoms in the benzo(chalcogen)diazole cores. Furthermore, current-voltage (I-V) experiments, combined with theoretical analyses, suggest that MEC plays a dominant role in modulating electron transport behaviors. Overall, our findings provide important insights into the interface-mediated charge transport exerted by chalcogen atoms within molecular devices, thereby enhancing the fundamental comprehension of these critical interactions.

P-i-n geometry perovskite solar cells (PSCs) offer simplified fabrication, greater amenability to charge extraction layers, and low-temperature processing over n-i-p counterparts. Self-assembled monolayers (SAMs) can enhance the performance of p-i-n PSCs but ultrathin SAMs can be thermally unstable. We report a thermally robust hole-selective layer comprised of nickel oxide (NiO _x ) nanoparticle film with a surface-anchored (4-(3,11-dimethoxy-7H-dibenzo[c,g]carbazol-7-yl)butyl)phosphonic acid (MeO-4PADBC) SAM that can improve and stabilize the NiO _x /perovskite interface. The energetic alignment and favorable contact and binding between NiO _x /MeO-4PADBC and perovskite reduced the voltage deficit of PSCs with various perovskite compositions and led to strong interface toughening effects under thermal stress. The resulting 1.53–electron-volt devices achieved 25.6% certified power conversion efficiency and maintained >90% of their initial efficiency after continuously operating at 65 degrees Celsius for 1200 hours under 1-sun illumination.

Insightful understanding of defect properties and preventionofdefect damage are among the biggest issues in the development of photoelectronicdevices based on wide-gap III-nitride semiconductors. Here, we haveinvestigated the vacancy-induced carrier nonradiative dynamics inwide-gap III-nitrides (GaN, AlN, and Al x Ga1-x N) by ab initio moleculardynamics and nonadiabatic (NA) quantum dynamics simulations sincethe considerable defect density in epitaxy samples. E-h recombinationis hardly affected by V-cation, which created shallow statesnear the VBM. Our findings demonstrate that V-N in AlN createsdefect-assisted nonradiative recombination centers and shortens therecombination time (& tau;) as in the Shockley-Read-Hall (SRH) model.In GaN, V-N improves the NA coupling between the CBM andthe VBM. Additionally, increasing x in the Al( x )Ga(1-x )Nalloys accelerates nonradiative recombination, which may be an importantissue in further improving the IQE of high Al-content Al x Ga1-x N alloys.These findings have significant implications for the improvement ofwide-gap III-nitrides-based photoelectronic devices.

Our research has been conducted on the charge transport properties of the single-crystal DPTTA and the cocrystal DPTTA-F4TCNQ using the density functional theory coupled with incoherent charge-hopping model. Charge mobility is primarily considered from the combination of reorganization energy and charge transfer integral, which are important parameters in model of the charge-hopping model. The reorganization energy of DPTTA in both single-crystal and cocrystal forms exhibits similar values. Consistent with the properties of super-exchange coupling and direct coupling when under the same type of coupling mechanism, it decreases with increasing distance from the core molecule. We conclude this section by using kinetic Monte Carlo combined with Einstein's equation to derive the charge mobility, and find it to be consistent with the theoretical analysis. In our study, we propose corresponding theoretical guidelines for the rational realization of the ambipolarity of D-A complexes, hoping to contribute to the understanding and rational design of the basic mechanism of D-A complexes.

Further enhancing the performance and stability of inverted perovskite solar cells (PSCs) is crucial for their commercialization. We report that the functionalization of multication and halide perovskite interfaces with an organometallic compound, ferrocenyl-bis-thiophene-2-carboxylate (FcTc ₂ ), simultaneously enhanced the efficiency and stability of inverted PSCs. The resultant devices achieved a power conversion efficiency of 25.0% and maintained >98% of their initial efficiency after continuously operating at the maximum power point for 1500 hours under simulated AM1.5 illumination. Moreover, the FcTc ₂ -functionalized devices passed the international standards for mature photovoltaics (IEC61215:2016) and have exhibited high stability under the damp heat test (85°C and 85% relative humidity).

Structural design of organic π-conjugated small molecules allows the energy band structure and electronic properties of the molecules to be tuned as needed, which provides a feasible strategy for enhancing the performance of optoelectronic devices. The introduction of bridging structures is a common structural modification method to adjust the rigidity and coplanarity of the molecular backbone, thus affecting the molecular packing. However, patterning of organic single-crystalline microstructures based on conjugated ladder molecules with different bridging structures still remains challenging for large-area integration of optoelectronic devices. In this paper, a controlled dewetting process is applied to obtain organic single-crystalline arrays with precise positioning and a regular morphology based on two isomers with silicon–oxygen bridging and their two carbon–oxygen-bridged analogues. Molecules with different bridging structures show disparate packing models due to the difference of dihedral angles and ring tensions. A microwire-array ultraviolet photodetector based on the oxygen–silicon-bridging ladder molecule exhibits a high light on/off ratio of 24 and a responsivity of 0.63 mA W^–1 owing to the effective π–π stacking governed by the molecular planarity. This work not only provides a universal method for the integration of organic optoelectronic devices but also explains the effect of bridging structure engineering on molecular assembly and optoelectronic performance.

Background: Endometriosis is a common, chronic gynecological disease. Laparoscopy is currently the preferred method of ovarian endometriosis. However, the safety and feasibility of laparoendoscopic single-site surgery for ovarian endometrioid cyst removal still need to be discussed. Objective: To explore the safety and feasibility of laparoendoscopic single-site (LESS) surgery versus conventional multiport laparoscopic (CMPL) surgery for the ovarian endometrioid cystectomy. Methods: We retrospectively analyzed the data of 47 patients who had undergone LESS and LESS ovarian cystectomy due to ovarian endometrioid cyst in our hospital from March 2018 to April 2019. The patients were classified into single-port group (14) and multiport group (33) based on surgical paths. The patients’ general characteristics and perioperative outcomes compared. Results: There were no significant statistical differences between the two groups (P>0.05) in the operation time and the maximum body temperature in 24 h after operation. There were significant statistical differences (all P<0.05) in postoperative decrease of Hb, intraoperative bleeding volume, total hospital stay and CS score. Conclusion: LESS for ovarian endometrioid cyst removal is safe and feasible, and it better than CMPL in relieving postoperative pain and inproving cosmetic effects and so on.

A major challenge for organic solar cell (OSC) research is how to minimize the tradeoff between voltage loss and charge generation. In early 2019, we reported a non-fullerene acceptor (named Y6) that can simultaneously achieve high external quantum efficiency and low voltage loss for OSC. Here, we use a combination of experimental and theoretical modeling to reveal the structure-property-performance relationships of this state-of-the-art OSC system. We find that the distinctive π–π molecular packing of Y6 not only exists in molecular single crystals but also in thin films. Importantly, such molecular packing leads to (i) the formation of delocalized and emissive excitons that enable small non-radiative voltage loss, and (ii) delocalization of electron wavefunctions at donor/acceptor interfaces that significantly reduces the Coulomb attraction between interfacial electron-hole pairs. These properties are critical in enabling highly efficient charge generation in OSC systems with negligible donor-acceptor energy offset.