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Defective grain boundaries (GBs) and surface trap states are detrimental to the efficiency and stability of perovskite solar cells (PSCs). In this research, ionic liquid (IL) is used to control the defect states at the perovskite surface and GBs. The newly formed (EMIm)xMA1–xPb[(BF4)xI1–x]3interlayer promotes secondary grain growth to diminish GBs; besides, EMIM+and BF4–fill the vacancies of MA+and I–and also passivate undercoordinated Pb2+trap states. The newly formed interface largely reduces the nonradiative recombination, thus enhancing the solar-cell performance to 19.0% (AM 1.5, 1 sun) with higher photovoltage and fill factor than the control device. Due to the hydrophobicity of the (EMIm)xMA1–xPb[(BF4)xI1–x]3interlayer, the unencapsulated device stability in 30 days is much better than the control device under relative humidity (RH) = 20%. This work highlights IL-induced secondary grain growth and a defect passivation method for efficient and stable PSCs.

Inorganic NiOxhas attracted tremendous attention in organic–inorganic hybrid perovskite solar cells (PSCs) in recent years but is relatively less used in all-inorganic PSCs. In this study, we have discovered and confirmed the detrimental interfacial reaction between NiOxand DMAI-containing CsPbI3inorganic perovskites. Thus, a self-assembled monolayer, Br-2PACz, is employed to modify the NiOxsurface to obstruct the adverse interfacial reaction and further improve the device performance. The results demonstrate that Br-2PACz modification on NiOxcan also improve interface contact, perovskite film morphology, and energy level alignments. Consequently, a champion power conversion efficiency (PCE) of 19.34% with a high open-circuit voltage (VOC) of 1.15 V is obtained for inverted NiOx/Br-2PACz-based CsPbI3PSCs compared to the reference NiOx-based PSC with a moderate PCE of 15.16% (VOC1.05 V). Moreover, the stabilities of both CsPbI3films and devices exhibited significant enhancement after Br-2PACz modification. The unpacked PSCs could maintain 80, 73, and 89% of the initial efficiency after aging in 30–35% RH for 960 h, heating at 60 °C for 48 h, and continuous illumination for 284 h, respectively, highly superior to the reference devices. Our work offers a facile and effective approach for developing high-performance inverted NiOx-based CsPbI3PSCs.

Air-processed perovskite solar cells (PSCs) with high photoelectric conversion efficiency (PCE) can not only further reduce the production cost but also promote its industrialization. During the preparation of the PSCs in ambient air, the contact of the buried interface not only affects the crystallization of the perovskite film but also affects the interface carrier transport, which is directly related to the performance of the device. Here, we optimize the buried interface by introducing 3-mercaptopropyltrimethoxysilane (MPTMS, (CH3O)3Si(CH2)3SH) on the nickel oxide (NiOx) surface. The crystallization of the perovskite film is improved by enhancing surface hydrophobicity; besides, the SH-based functional group of MPTMS passivates the uncoordinated lead at the interface, which effectively reduces the defects at the bottom interface of perovskite and inhibits the nonradiative recombination at the interface. Moreover, the energy level between the NiOxlayer and the perovskite layer is better matched. Based on multiple functions of MPTMS modification, the open circuit voltage of the device is obviously improved, and efficient air-processed methylamine-free (MA-free) PSCs are realized with PCE reaching 21.0%. The device still maintains the initial PCE of 85% after 1000 h aging in the glovebox. This work highlights interface modification in air-processed MA-free PSCs to promote the industrialization of PSCs.

Zero drift can severely deteriorate the stability of the light–dark current ratio, detectivity, and responsivity of photodetectors. In this paper, the effects of a [6,6]-phenyl-C61-butyric acid methyl ester (PCBM)-doped perovskite-based photodetector device on the inhibition of zero drift under dark state are discussed. Two kinds of photodetectors (Au/CH3NH3PbIxCl3–x/Au and Au/CH3NH3PbIxCl3–x:PCBM/Au) were prepared, and the materials and photodetector devices were measured by scanning electron microscopy, X-ray diffraction, photoluminescence, ultraviolet absorption spectra, and current–voltage and current–time measurements. It was found that similar merit parameters, including light–dark current ratio (∼102), detectivity (∼1011Jones), and responsivity were obtained for these two kinds of photodetectors. However, the drift of Au/CH3NH3PbIxCl3–x:PCBM/Au devices is negligible, while a drift of ∼0.2 V exists in Au/CH3NH3PbIxCl3–x/Au devices. A new model is proposed based on the hindering theory of ion (vacancy) migration, and it is believed that the dopant PCBM can hinder the ion (vacancy) migration of perovskite materials to suppress the phenomenon of zero drift in perovskite-based photodetectors.

N-type tin oxide (SnO2) films are commonly used as an electron transport layer (ETL) in perovskite solar cells (PSCs). However, SnO2films are of poor quality due to facile agglomeration under a low-temperature preparation method. In addition, energy level mismatch between the SnO2and perovskite (PVK) layer as well as interfacial charge recombination would cause open-circuit voltage loss. In this work, alkali metal oxalates (M-Oxalate, M = Li, Na, and K) are doped into the SnO2precursor to solve these problems. First, it is found that the hydrolyzed alkali metal cations tend to change colloid size distribution of SnO2, in which Na-Oxalate with suitable basicity leads to most uniform colloid size distribution and high-quality SnO2-Na films. Second, the electron conductivity is enhanced by slightly agglomerated SnO2-Na, which facilitates the transmission of electrons. Third, alkali metal cations increase the conduction band level of SnO2in the sequence of K+, Na+, and Li+to promote band alignment between ETLs and perovskite. Based on the optimized film quality and energy states of SnO2-Na, the best PSC efficiency of 20.78% is achieved with a significantly enhanced open-circuit voltage of 1.10 V. This work highlights the function of alkali metal salts on the colloid particle distribution and energy level modulation of SnO2.