Cu‐doped‐CdS and In‐doped‐CdS cosensitized (Cu‐doped‐CdS/In‐doped‐CdS) quantum dot solar cells (QDSCs) are introduced here. Different cosensitized sequences, doping ratios, and the thickness (SILAR cycles) of Cu‐doped‐CdS and In‐doped‐CdS are discussed. Compared with undoped CdS QDSCs, the short circuit current density, UV‐Vis absorption spectra, IPCE (monochromatic incident photon‐to‐electron conversion), open circuit voltage, and so on are all improved. The photoelectric conversion efficiency has obviously improved from 0.71% to 1.28%.

Y-shaped carbon nanofibers as a multi-branched carbon nanostructure have potential applications in electronic devices. In this article, we report that several types of Y-shaped carbon nanofibers are obtained from ethanol flames. These Y-shaped carbon nanofibers have different morphologies. According to our experimental results, the growth mechanism of Y-shaped carbon nanofibers has been discussed and a possible growth model of Y-shaped carbon nanofibers has been proposed.

In order to optimize the charge transfer path in quantum dot sensitized solar cells (QDSCs), we employed successive ionic layer adsorption and reaction method to dope CdSe with Co for fabricating CdS/Co‐doped‐CdSe QDSCs constructed with CdS/Co‐doped‐CdSe deposited on mesoscopic TiO₂ film as photoanode, Pt counter electrode, and sulfide/polysulfide electrolyte. After Co doping, the bandgap of CdSe quantum dot decreases, and the conduction band and valence band all improve, forming a cascade energy level which is more conducive to charge transport inside the solar cell and reducing the recombination of electron‐hole thus improving the photocurrent and ultimately improving the power conversion efficiency. This work has not been found in the literature.

Perovskite thin films with excellent optical semiconductor and crystallization properties and superior surface morphology are normally considered to be vital to perovskite solar cells (PSCs). In this paper, we systematically survey the process of modulating surface morphology and optical semiconductor and crystallization properties of methylammonium lead iodide film by controlling doping of K⁺ for PSC prepared in air and propose the mechanism of large K⁺-doped perovskite grain formation related to crystallization speed. The increase in the crystallization speed leads to the production of large grains without localized-solvent-vapor (LSV) pores via moderate doping of K⁺, and the exorbitant crystallization speed induces super large grains with LSV pores via excessive doping of K⁺. Furthermore, the semiconductor properties (absorption band edge wavelength, PL emission peak wavelength, energy band gap) of perovskite film can be significantly tuned by controlled doping of K⁺. The investigation of the detailed process of modulating surface morphology and semiconductor properties of perovskite thin film by controlled doping of K⁺ may provide guidance and pave the way for superior component design of absorption materials for cost-efficient PSCs.

Lead nitrate mixed with alkali in solution generates insoluble precipitates. The morphology and microstructure of the precipitates are dramatically influenced by the chloride anion concentration in the lead nitrate precursor solution. To intensively investigate the effect of the chloride anion concentration, we performed a series of controllable experiments with different concentrations of chloride anions (the concentration ratios of Pb²⁺ : Cl ⁻ = 1 : 0, 1 : 0.2, 1 : 0.5, 1 : 1, 1 : 2, and 1 : 3 in the solution) at different solution temperatures of 90 and 80 °C. The results reveal that, with the increasing concentration of chloride anions, the colour of the precipitates changes from yellow to red and finally to white; the morphology of the precipitates changes from plate-like to rod-like; the crystal structure of the precipitates changes from β-PbO to a mixture of β- and α-PbO (or α-PbO), and finally to lead hydroxide. These results suggest that adding chloride could lead to the formation of rod-like morphology and simultaneously could restrain the dehydration of Pb(OH)₂ .

High-class perovskite film with beautiful surface morphology (such as large-size grain, low defect density, good continuity and flatness) is normally believed to be a very important factor for high-efficiency perovskite solar cells (PSCs). Here, we report a modified sequential deposition route through localized-liquid-liquid-diffusion (LLLD) for qualified perovskite multi-crystalline thin films with micrometer-scaled grains for solar cells. We adopted a contact-type drop method to drop Methylammonium iodide (MAI) solution and have successfully used high-concentration MAI solution (73 mg/mL) to transform PbI₂ film into high-class perovskite film via our route. A high efficiency of 10.7% was achieved for the device with spongy carbon film deposited on a separated FTO-substrate as a counter electrode under one sun illumination, which is the highest efficiency (as 2.5 times as previous efficiency) ever recorded in perovskite solar cells with a such spongy carbon/FTO composite counter electrode. The preparation techniques of high-class perovskite thin films under ambient conditions and the cheap spongy carbon/FTO composite counter electrode are beneficial for large-scale applications and commercialization.