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Flexible perovskite solar cells (PSCs) have received increasing attention in wearable and portable devices over the past ten years. The low-temperature process of electron transport layer plays a key role in fabricating flexible PSCs. In this paper, we improve the performance of flexible PSCs by controlling the thermodynamic procedure in the low-temperature annealing process of solution-processed TiO2 layers and modulating the precursor concentration of (6,6)-phenyl c61 butyric acid methyl ester (PC61BM) deposited on fluorine-doped tin oxide (FTO)/TiO2 substrate. The results show that slowing down evaporation rate of residual solvent and adopting PC61BM of appropriate precursor concentration are confirmed to be effective methods to improve the performance of flexible PSCs. We also demonstrate carbon electrode-based flexible PSCs. Our work expands the feasibility of low temperature process for the development of flexible perovskite photodetectors and light-emitting diodes, as well as flexible PSCs.

It is crucial to find a good material as a hole transport layer (HTL) to improve the performance of perovskite solar cells (PSCs), devices with an inverted structure. Polyethylene dioxythiophene-poly (styrene sulfonate) (PEDOT:PSS) and inorganic nickel oxide (NiOx) have become hotspots in the study of hole transport materials in PSCs on account of their excellent properties. In our research, NiOx and PEDOT: PSS, two kinds of hole transport materials, were prepared and compared to study the impact of the bottom layer on the light absorption and morphology of perovskite layer. By the way, some experimental parameters are simulated by wx Analysis of Microelectronic and Photonic Structures (wxAMPS). In addition, thin interfacial layers with deep capture levels and high capture cross sections were inserted to simulate the degradation of the interface between light absorption layer and PEDOT:PSS. This work realizes the combination of experiment and simulation. Exploring the mechanism of the influence of functional layer parameters plays a vital part in the performance of devices by establishing the system design. It can be found that the perovskite film growing on NiOx has a stronger light absorption capacity, which makes the best open-circuit voltage of 0.98 V, short-circuit current density of 24.55 mA/cm2, and power conversion efficiency of 20.01%.

we insert (6,6)-phenyl c61 butyric acid methyl ester (PC61BM) interlayer of different precursor solution concentrations between low-temperature TiO2 electron transport layer (ETL) and light absorption layer to modify charge carrier transporting, mitigate hysteresis and improve perovskite film quality. The results show that the TiO2 / perovskite interface, the perovskite film morphology and photo physical properties can be modified by optimizing the precursor solution concentrations of PC61BM interlayer, which facilitates the electron extraction from perovskite absorption layer to TiO2 ETL and reduces the hysteresis.

TiO2 is an important electron transport material in perovskite solar cells (PSCs). Some researchers have prepared dense TiO2 particles and mesoporous TiO2, but there are few reports on preparation of TiO2 nanosheets for solar cells. We have prepared in-situ controllable TiO2 nanosheet array on the fluorine-doped tin oxide (FTO) substrate with multiple spin-coating method, and the nanosheets were horizontally arranged in order with good shape consistency. Our research provides references for the preparation of solar cells with TiO2 nanosheets as electron transport layer (ETL).

As a new type of solar cells, perovskite solar cells (PSCs) have received widespread attention. The grain growth and surface morphology of perovskite thin films are considered to have an important influence on the performance of PSCs. In this paper, the K+ was introduced into the CH3NH3PbI3 (MAPbI3) and the effect of different doping concentration on the morphology, photophysical properties, and semiconductor characteristics of the perovskite films was investigated. From experiments, we found that the incorporation of low-concentration K+ has a passivation effect on the grain boundaries, which reduces the defect density at interface. The phase transition and obvious red shift of MAPbI3 could be seen under high doping concentration in XRD pattern and absorption spectrum, respectively. The modulation of the perovskite layer major charge carrier type was observed when K+ was introduced, which laid a basis for future investigation on inverted homo-junction solar cells.

The investigation of crystal growth is crucial for us to improve the film quality and photophysical properties of CH3NH3PbI3 (MAPbI3). In the two-step spin-coating process, the crystal structure could be modulated by controlling the growth conditions of PbI2 and CH3NH3I (MAI) layers. In this paper, the PbI2 layer was treated with annealing under different times. A liquid&ndash, liquid diffusion (LLD) mechanism is proposed to modify the deposition of MAI precursor solution and enhance the flatness of organic&ndash, inorganic hybrid perovskite film. Furthermore, the perovskite films are prepared using different concentrations of MAI. The evolution process of perovskite structure is observed by modulating the concentration of MAI. The spin-coating of moderate MAI tends to form high quality MAPbI3 films with enhanced absorption and carrier extraction capabilities. The high concentration of MAI would cause the perovskite phase transition, which provides a novel perspective to modulate the structure of organic&ndash, inorganic hybrid perovskite in the two-step spin-coating process, although it deteriorates the device performance.

Perovskite components have tremendous influence on the film quality and device performance. There are obvious impurity defects, holes, etc. in the films of conventional perovskite solar cells (PSCs). In this work, the perovskite component was tuned to [HC(NH2)2]0.3(CH3NH3)0.7PbI2.4Cl0.3Br0.3 (FA0.3MA0.7PbI2.4Cl0.3Br0.3) via cation and anion co-mixing, it was observed that the residual PbI2 at perovskite film had a good passivation effect on the grain boundaries and further ameliorated the quality of the film. The photoelectric conversion efficiency (PCE) of low-cost carbon electrode-based photovoltaic devices we prepared increased from 8.58% to 12.40%. Our work will also be more beneficial to the commercialization of PSCs and the preparation of other optoelectronic devices.

Cells are the smallest living units of a human body’s structure and function, and their behaviors should not be ignored in human physiological and pathological metabolic activities. Each cell has a different scale, and presents distinct responses to specific scales: Vascular endothelial cells may obtain a normal function when regulated by the 25 µm strips, but de-function if the scale is removed; stem cells can rapidly proliferate on the 30 nm scales nanotubes surface, but stop proliferating when the scale is changed to 100 nm. Therefore, micro and nano scales play a crucial role in directing cell behaviors on biomaterials surface. In recent years, a series of biomaterials surface with micro and/or nano scales, such as micro-patterns, nanotubes and nanoparticles, have been developed to control the target cell behavior, and further enhance the surface biocompatibility. This contribution will introduce the related research, and review the advances in the micro/nano scales for biomaterials surface functionalization.