Nickel oxide (NiO) materials with excellent stability and favorable energy bands are desirable candidates for hole‐selective contact (HSC) of inverted perovskite solar cell (PSC). However, studies that focus on addressing interfacial issues, which are induced by the poor NiO/perovskite contact or other defects, are scarce. In this study, a facile one‐step hydrothermal strategy is demonstrated for the development of a 3 D NiO nanowall (NW) film as a promising HSC. The new NiO NWs HSC exhibits a robust and homogenous mesoporous network structure, which improved the NiO/perovskite interface contact, passivated the interfacial defect and improved the quality of the perovskite film. The optimized interface features enabled a power conversion efficiency (PCE) approaching 18 %. A diethanolamine (DEA) interlayer was introduced to further passivate the intrinsic defect of the NiO surface, resulting in better charge transfer with suppressed recombination loss. As a result, the champion PCE of the NiO NWs/DEA‐based device was increased to 19.16 % with a high open‐circuit voltage (≈1.11 V) and fill factor (>80 %), which is prominent in methylammonium lead iodide‐based inverted PSCs. Furthermore, the device exhibited better stability and lower hysteresis behavior than a conventional solution‐based NiO nanocrystal device.

A one-step high-temperature hydrated-sulfate assisted solvothermal method has been developed to synthesize TiO(2)/sulfide nanocomposite spheres. Different hybrid spheres of TiO(2)/CdS, TiO(2)/Cu(2)S, TiO(2)/FeS, TiO(2)/Co(9)S(8), and TiO(2)/ZnS were readily prepared by exploiting different hydrated sulfate. The hydrated sulfate has been proved to play multifunctional roles during the synthetic process, such as spherical template, water supplier, and composition controller. Nanocrystal CdS can be reduced from CdSO(4) at a high solvothermal temperature of 350 °C, and the TiO(2)/CdS nanocomposite spheres prepared by this method exhibit superior visible-light-driven photocatalytic efficiency because of its effective heterointerface and high crystallinity.

Inverted perovskite solar cells (PSCs) demonstrate attractive features in developing an air-stable photovoltaic device, by employing inorganic hole transport layers (HTLs). However, their power conversion efficiencies are still inferior to that of mesoporous n-i-p devices, mainly attributed to the undesirable hole extraction and interfacial recombination loss. Here, we design a novel one-dimensional NiO nanotube (NT) nanoforest as efficient mesoporous HTLs. Such a NiO NT mesoporous structure provides a highly conductive pathway for rapid hole extraction and depresses interfacial recombination loss. Furthermore, excellent light capturing could be achieved by optimizing the length and branch growth of the NiO NT nanoforest, which mimics the evolution of the natural forest. Therefore, this inverted mesoporous PSCs yield an optimal efficiency of 18.77%, which is still prominent in state-of-the-art NiO-based devices. Alternatively, the mesoporous device exhibits greatly improved long-term stability. This work provides a new design perspective for developing high-performance inverted PSCs.

No abstract

No abstract

No abstract

No abstract

In this P-I-N architecture, the NiO with advantages of high transmittance and wide bandgap (3.4-4.0 eV), [7][8][9] is the most popular hole-transporting layer (HTL). However, the efficiency development of NiO-based devices is still lagging behind normal TiO 2 -based PSCs. [10][11][12][13] The inferior performance is closely related to the undesirable hole extraction efficiency at NiO/ perovskite interface. [14][15][16][17] This would lead to severe charge accumulation and nonradiative recombination, which is mainly reflected in the loss of open-circuit voltage (V oc ) and fill factor (FF). [14,[18][19][20][21] Therefore, how to enhance interfacial hole extraction efficiency is critical for efficient NiO-based devices. [22,23] A popular strategy to ensure fast hole transport at NiO/perovskite interface is doping NiO to optimize its p-type conductivity and energy level. [24][25][26][27][28] Up to present, various high-performance PSCs have been reported for doped NiO HTLs, such as Zn:NiO (19.60%), [26] Cu:NiO (20.15%), [27] Cs:NiO (19.35%), [28] and K:NiO (18.05%). [29] Lately, the champion PCEs of 20.8% have also been realized for Al:NiO-based device. [30] Despite these efforts, it is worth noting that such ideally doped film needs to be uniform and thin enough (<30 nm), otherwise the numerous crystal lattice defects induced by ionic doping would also degrade the carrier mobility. [31,32] The complicated and uncontrollable process of this approach makes it still challenging, develop a more reliable and universal strategy is imperative.Ration design of interface materials, such as metal oxide, carbon materials, and other buffer interlayers, would be a promising solution, as they can well match with the perovskite layer, and combine high conductivity with fast charge transport to minimize the nonradiative recombination loss. [33][34][35] For example, Li et al. incorporated the unique CNT@graphene hybrid nanostructure at perovskite/Spiro-OMeTAD interface to optimize the electrical performance and energy level alignment. The efficient charge collection, optimized hole transport, and reduced recombination result in the performance of normal TiO 2 -based device up to 19.56%. [33] Regrettably, there are few works focusing on interface interlayer design in P-I-N devices. It is of great significance to seek efficient material candidates to modify NiO/perovskite interface.Herein, we design the unique NiO x /carbon heterostructures (NCHs) as anode buffer interlayer for inverted NiO-based PSCs. Such NCHs interlayer offer the huge superiority for hole extraction and transportation at anode An efficient hole transport layer (HTL) with desirable charge separation and hole extraction efficiency is crucial for inverted perovskite solar cells. However, the interfacial trap recombination loss and mismatched band alignment limit the actual performance of device, especially the open-circuit voltage (V OC ). To address this issue, a unique NiO x /carbon heterostructure is designed as efficient anode interlayer for optimizing the interf...