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Well-crystallized maricite NaFePO4 is thermodynamically stable but electrochemically inactive toward sodium owing to the close packed framework. An efficient activation-approach is to construct amorphous composites with carbon by the complex and energy-intensive synthetic process. Here, a facile approach was proposed by the combination of low-temperature sintering and ball milling, which is environmentally friendly and suitable for scalable synthesis. Quasi-amorphous maricite NaFePO4 was first prepared via reducing the calcination temperature to 350 °C. Amorphous composite NaFePO4/C was further obtained by ball milling of NaFePO4-350 °C with super P, which delivers a reversible capacity of 134 mAh g−1, closing to its theoretical capacity. More impressively, the NaFePO4/C electrode still demonstrates decent capacity-retention of ∼75.4% over 1000 cycles, which is encouraging for future research. Pairing with hard carbon anode, the (+)NaFePO4/C//HC(−) sodium-ion full cell delivers outstanding power density (169.9 Wh kg−1 calculated based on the total mass of positive and negative electrodes) and excellent cycling stability (84.5% capacity retention after 500 cycles at 5C), exhibiting powerful competitiveness compared with previously reported NaFePO4 based sodium-ion full cells. These results demonstrate the practical potential of maricite NaFePO4 cathode through low-temperature sintering. [ABSTRACT FROM AUTHOR]

In order to fabricate nickel oxide (NiOX)-based perovskite solar cells with high efficiency and stability, adverse reaction and lattice mismatch are two urgent problems to be overcome. In this respect, interface engineering was carried out by multi-layer passivation NiOX HTLs (NiOX/2PACz/Poly-TPD/PEAI) to provide optimized interface contact between NiOX and perovskite, ameliorate band alignment, and saturate the defect states. Application of 2PACz avoids direct contact of the hydroxyl groups (which causes degeneration of a device), improves conductivity, and reduces interfacial defects. The poly-TPD modification can provide an appropriate band alignment at the interface of NiOX/perovskite. PEAI was used to modify the Poly-TPD surface, and its −NH3 group can passivate unbonded Pb ions of perovskite. Thus, compared with previously reported single-function passivation materials, the multilayer passivation proposed in this paper integrates multiple functions. As a result, the NiOX/2PACz/Poly-TPD/PEAI-based wide bandgap PSCs obtain a champion power conversion efficiency (PCE) of 20.21% and maintain over 95% of their initial PCE values after storage in a nitrogen atmosphere for 1000 h. This finding provides a practical approach for fabricating high-performance regular PSCs with NiOX-based HTLs and supports their commercialization. [ABSTRACT FROM AUTHOR]

Although perovskite solar cells (PSCs) based on SnO2 have reached a power conversion efficiency (PCE) over 25%, large-scale fabrication remains the main obstacle to the commercialization of PSCs. Therefore, considering the process compatibility, low-temperature processing and large-area fabrication technologies have received widespread attention as those are ideal for upscaling of single and tandem devices. Herein, we demonstrated an effective atomic layer deposition (ALD) process by using H2O2 as an oxygen source and the deposition temperatures can be lowered up to 50 °C due to the high activity of H2O2. The low temperature deposition enables conformal coverage of the substrate and results in a pinhole-free film with high optical transmittance, excellent electron extraction properties, and large area uniformity. Notably, a high PCE of 20.70% is achieved for single junction PSCs based on ALD-SnO2 (50 °C). When the ALD-SnO2 applied to p-i-n structure perovskite/silicon heterojunction tandem solar cell, an efficiency of 26.67% was obtained. The results demonstrate the potential of the low-temperature ALD processed metal oxide for large-scale manufacturing of optoelectronic devices with competitive performances. [ABSTRACT FROM AUTHOR]