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Despite the success of solution processed nickel oxide (s-NiO x) as the hole transporting layer (HTL) in organic solar cells, applying s-NiO x in perovskite solar cells (PVSCs) is not that straight forward. The reported power conversion efficiencies (PCEs) of the s-NiO x based PVSCs span a wide range from 8% to over 20% even with a similar recipe. Here, we report that one of the causes for the performance discrepancy might be the large surface dipole on the s-NiO x surface. We find that the perovskite deposited on the as-prepared sol-gel derived s-NiO x has large number of defects at the s-NiO x /perovskite interface. Based on the in-depth mechanism study with various spectroscopy techniques, we propose that the strong surface dipole of the s-NiO x composite film induces adhesion of perovskite precursor ions on the surface of s-NiO x during the perovskite film formation and creates defects in the perovskite crystals at the interface. Such interfacial dipole-ion attachment has been demonstrated can be dissociated by ultraviolet (UV) light soaking experiment. The high energy of the UV light helps to dissociate the physical dipole-ion attachment and mobilize the ions to accommodate the perovskite defect sites. The defect density of the perovskite film on s-NiO x has been significantly reduced by an amount of 4.1 × 1017 cm−3 after the UV light soaking as evidenced by photothermal deflection spectroscopy (PDS) measurement. By treating the s-NiO x surface with a dipolar molecule n-Butylamine, the surface dipole of the s-NiO x film is efficiently reduced and it significantly reduces the defect density in the perovskite film. As a result, the PVSCs based on the n-Butylamine treated s-NiO x layer have achieved a dramatical enhancement in PCE to 18.9% with decent stability at the maximum power point tracking. It is believed that this work provides insight and strategy to develop highly reproducible PVSCs with solution derived metal oxide as interlayers. Image 1 • The surface dipole in NiO x is found to affect the crystallization and performance of perovskite solar cells. • The defect density in CH 3 NH 3 PbI 3 film has reduced after reducing the surface dipole in NiO x. • The perovskite solar cell based on the modified NiO x layer achieves a PCE of 18.9% with decent stability. [ABSTRACT FROM AUTHOR]

Flexible hygroelectric generators (HEGs) that derive affordable and sustainable electricity power from omnipresent moisture are promising candidates for smart textile electronics. However, the desired compatibility of high output current and continuous operating voltage is still challenging for wearable HEGs to meet the ever-increasing nanotechnological requirements. Herein, we rationally design and finely synthesize conductive carbonized silk fabrics with in situ growth of SnO/SnO 2 nanosheet arrays, which are successfully employed to fabricate high-efficiency wearable HEGs with a maximal power density of 26.66 μW·cm−2 by sandwiching with MXene/cotton fabrics and Al electrodes. Impressively, the vertically interlaced SnO/SnO 2 nanosheet arrays supply abundant nanofluidic channels for rapid water diffusive flow with a high flow potential. Combined with the excellent moisture absorption and retention of MXene/cotton textiles, these prepared HEGs process sustained voltage and current outputs of 0.932 V and 0.434 mA over 20,000 s. These flexible HEGs are capable of application in self-powered sensors and micro power supplies, delivering a fresh strategy for the rational design of high-performance and sustainable textile-based electronics. [Display omitted] • A hygroelectric generator based on nanofluidic channels toward was developed. • The vertically interlaced SnO/SnO 2 nanosheet arrays supply abundant nanofluidic channels for a high flow potential. • The asymmetric fabrics structure incudes a proton concentration gradient for the enables charge separation. • These textile-based HEGs demonstrate an excellent performance with a maximal power density of 26.66 μW·cm−2. [ABSTRACT FROM AUTHOR]

A new bipolar host material (PBCz-PO) consisting a phosphinic amide is developed to show a resonance effect. It possesses quite high triplet energy (2.76 eV), and this high triplet energy make it suitable to be blue host in phosphorescent organic light-emitting diodes (PHOLEDs). The device with PBCz-PO as a host and FIrpic as a dopant achieved a maximum current efficiency ( η c ) of 31.5 cd/A, a maximum power efficiency ( η p ) of 31.0 lm/W and a maximum external quantum efficiency (EQE) of 13.4% as well as low driving voltage. [ABSTRACT FROM AUTHOR]

Non-wetting hole transport materials (HTMs) have great potential in facilitating large-sized perovskite crystal growth and enhancing device stability by opposing moisture ingress, However, the severe non-wetting issue limits the wide application of these materials in low-temperature solution-processed inverted planar perovskite solar cells (PVSCs), and corresponding devices are rarely reported. Here, a facile ultraviolet-ozone (UVO) modification method is demonstrated to overcome this issue. By carefully controlling the UVO modification time, the surface wettability of poly-TPD can be tuned without affecting the bulk properties of the film, hence perovskite films with desired grain size and excellent coverage can be deposited via a one-step spin-coating method. Benefiting from the high-quality perovskite, well-matched energy level alignment and hydrophobic property of poly-TPD, the resulting PVSCs show a champion power conversion efficiency of 18.19% with significantly enhanced stability as compared to the PEDOT:PSS counterparts. Moreover, the UVO modification approach also demonstrates its validity when being extended to other hydrophobic HTMs. This work not only provides a general strategy to broaden the selection pool of HTMs for solution-processed inverted planar PVSCs, but also may triggers the exploration of more advanced strategies to make non-wetting HTMs applicable in solution-processed inverted planar PVSCs. [ABSTRACT FROM AUTHOR]