Interface Dipole Management of D-A-Type Molecules for Efficient Perovskite Solar Cells.

Interfacial engineering of perovskite films has been the main strategies in improving the efficiency and stability of perovskite solar cells (PSCs). In this study, three new donor-acceptor (D-A)-type interfacial dipole (DAID) molecules with hole-transporting and different anchoring units are designed and employed in PSCs. The formation of interface dipoles by the DAID molecules on the perovskite film can efficiently modulate the energy level alignment, improve charge extraction, and reduce non-radiative recombination. Among the three DAID molecules, TPA-BAM with amide group exhibits the best chemical and optoelectrical properties, achieving a champion PCE of 25.29% with the enhanced open-circuit voltage of 1.174 V and fill factor of 84.34%, due to the reduced defect density and improved interfacial hole extraction. Meanwhile, the operational stability of the unencapsulated device has been significantly improved. Our study provides a prospect for rationalized screening of interfacial dipole materials for efficient and stable PSCs.

Monolithically-grained perovskite solar cell with Mortise-Tenon structure for charge extraction balance.

Although the power conversion efficiency values of perovskite solar cells continue to be refreshed, it is still far from the theoretical Shockley-Queisser limit. Two major issues need to be addressed, including disorder crystallization of perovskite and unbalanced interface charge extraction, which limit further improvements in device efficiency. Herein, we develop a thermally polymerized additive as the polymer template in the perovskite film, which can form monolithic perovskite grain and a unique "Mortise-Tenon" structure after spin-coating hole-transport layer. Importantly, the suppressed non-radiative recombination and balanced interface charge extraction benefit from high-quality perovskite crystals and Mortise-Tenon structure, resulting in enhanced open-circuit voltage and fill-factor of the device. The PSCs achieve certified efficiency of 24.55% and maintain >95% initial efficiency over 1100 h in accordance with the ISOS-L-2 protocol, as well as excellent endurance according to the ISOS-D-3 accelerated aging test.

Protective effects of electroacupuncture on polycystic ovary syndrome in rats: Down-regulating Alas2 to inhibit apoptosis, oxidative stress, and mitochondrial dysfunction in ovarian granulosa cells.

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder affecting women at reproductive age. The therapeutic effect of electroacupuncture (EA) on PCOS has been revealed, while the anti-PCOS mechanisms of EA have not been fully explored. In this study, PCOS were induced in rats by daily injection with dehydroepiandrosterone (DHEA) for 20 days and EA treatment was performed for 5 weeks. The mRNA expression profiles in ovarian tissues from control, PCOS, and EA-treated rats were examined by high-throughput mRNA sequencing. 5'-aminolevulinate synthase 2 (Alas2), a vital rate-limiting enzyme of the heme synthesis pathway, was selected to be further studied. PCOS led to the upregulation of Alas2 mRNA, whereas EA treatment restored this change. In vitro, primary ovarian granulosa cells (GCs) were challenged with H2O2 to mimic the oxidative stress (OS) state in PCOS. H2O2 induced apoptosis, OS, mitochondrial dysfunction, as well as Alas2 overexpression in GCs, while lentivirus-mediated Alas2 knockdown evidently restrained the above impairments. In summary, this study highlights the crucial role of Alas2 in cell apoptosis, OS, and mitochondrial dysfunction of PCOS GCs and provides potential therapeutic candidates for further investigation on PCOS treatment.

Orientated crystallization of FA-based perovskite via hydrogen-bonded polymer network for efficient and stable solar cells.

Incorporating mixed ion is a frequently used strategy to stabilize black-phase formamidinum lead iodide perovskite for high-efficiency solar cells. However, these devices commonly suffer from photoinduced phase segregation and humidity instability. Herein, we find that the underlying reason is that the mixed halide perovskites generally fail to grow into homogenous and high-crystalline film, due to the multiple pathways of crystal nucleation originating from various intermediate phases in the film-forming process. Therefore, we design a multifunctional fluorinated additive, which restrains the complicated intermediate phases and promotes orientated crystallization of α-phase of perovskite. Furthermore, the additives in-situ polymerize during the perovskite film formation and form a hydrogen-bonded network to stabilize α-phase. Remarkably, the polymerized additives endow a strongly hydrophobic effect to the bare perovskite film against liquid water for 5 min. The unencapsulated devices achieve 24.10% efficiency and maintain >95% of the initial efficiency for 1000 h under continuous sunlight soaking and for 2000 h at air ambient of ~50% humid, respectively.

Underlying Interface Defect Passivation and Charge Transfer Enhancement via Sulfonated Hole-Transporting Materials for Efficient Inverted Perovskite Solar Cells.

To date, numbers of polymeric hole-transporting materials (HTMs) have been developed to improve interfacial charge transport to achieve high-performance inverted perovskite solar cells (PSCs). However, molecular design for passivating the underlying surface defects between perovskite and HTMs is a neglected issue, which is a major bottleneck to further enhance the performance of the inverted devices. Herein, we design and synthesize a new polymeric HTM PsTA-mPV with the methylthiol group, in which a lone pair of electrons of sulfur atoms can passivate the underlying interface defects of the perovskite more efficiently by coordinating Pb2+ vacancies. Furthermore, PsTA-mPV exhibits a deeper highest occupied molecular orbital (HOMO) level aligned with perovskite due to the π-acceptor capability of sulfur, which improves interfacial charge transfer between perovskite and the HTM layer. Using PsTA-mPV as a dopant-free HTM, the inverted PSCs show 20.2% efficiency and long-term stability, which is ascribed to surface defect passivation, well energy-level matching with perovskite, and efficient charge extraction.

Self-Powered and Low-Noise Perovskite Photodetector Enabled by a Novel Dopant-Free Hole-Transport Material with Bottom Passivation for Underwater Blue Light Communications.

Designing dopant-free hole-transport materials (HTMs) is a facile and effective strategy to realize high-performance organic-inorganic hybrid perovskite (OIHP) photodetectors. Herein, a novel phenothiazine polymer, poly[4-(10H-phenothiazin-10-yl)-N,N-bis(4-methoxyphenyl)aniline] (PPZ-TPA), was synthesized and employed as a promising HTM in OIHP photodetectors. The triphenylamine donor unit was combined with a phenothiazine core, furnishing the polymer with a suitable highest occupied molecular orbital level, favorable thermal stability, and appropriate film morphology. The sulfur atom in the phenothiazine functional group can intentionally passivate the undercoordinated Pb2+ of OIHP films, suppressing nonradiative recombination and yielding an ultralow dark current density of 1.26 × 10-7 A cm-2 under -0.1 V, as well as a low-noise current of 3.75 × 10-13 A Hz-1/2 at 70 Hz. Encouragingly, the self-powered PPZ-TPA-based OIHP photodetectors were successfully integrated into a blue light communication system for the first time, demonstrating their application for receiving and transmitting light signals with a transmission rate of 300 bps. In addition, the PPZ-TPA-based devices exhibit nearly 1 year shelf stability without obvious degradation. We believe that PPZ-TPA demonstrates great potential to achieve high-performance perovskite photodetectors, also providing a strategy for the design of novel HTMs.

Tailored Polymeric Hole-Transporting Materials Inducing High-Quality Crystallization of Perovskite for Efficient Inverted Photovoltaic Devices.

For achieving high-performance p-i-n perovskite solar cells (PSCs), hole transporting materials (HTMs) are critical to device functionality and represent a major bottleneck to further enhancing device stability and efficiency in the inverted devices. Three dopant-free polymeric HTMs are developed based on different linkage sites of triphenylamine and phenylenevinylene repeating units in their main backbone structures. The backbone curvatures of the polymeric HTMs affect the morphology and hole mobility of the polymers and further change the crystallinity of perovskite films. By using PTA-mPV with moderate molecular curvature, p-i-n PSCs with high efficiency of 19.5% and long-term stability can be achieved. The better performance is attributed to the more effective hole extraction ability, higher charge-carrier mobility, and lower interfacial charge recombination. Furthermore, these three polymeric HTMs are synthesized without any noble metal catalyst, and show great advantages in future application owing to the low-cost.