No abstract

A novel technique for bonding polymer substrates using PDMS-interface bonding is presented in this paper. This novel bonding technique holds promise for achieving precise, well-controlled, low temperature bonding of microfluidic channels. A thin (10-25 µm) poly(dimethylsiloxane) (PDMS) intermediate layer was used to bond two poly(methyl methacrylate) (PMMA) substrates without distorting them. Microchannel patterns were compressed on a PMMA substrate by a hot embossing technique first. Then, PDMS was spin-coated onto another PMMA bare substrate and cured in two stages. In the first stage, it was pre-cured at room temperature for 20 h to increase the viscosity. Subsequently, it was bonded to the hot embossed PMMA substrate. In the second stage, PDMS was completely cured at 90 • C for 3 h and the bonding was successfully achieved at this relatively low temperature. Tensile bonding tests showed that the bonding strength was about 0.015 MPa. Microfluidic channels with dimensions of 300 µm × 1.6 cm × 100 µm were successfully fabricated using this novel bonding method.

Lead‐halide perovskite quantum dots (QDs) have attracted substantial attention due to their great potential in solution‐processed optoelectronic applications. The current synthetic method mostly relies on the binary‐precursor strategy, which significantly restricts the reaction yield and elemental regulation, leading to extremely high material cost. Herein, a more versatile ternary‐precursor method to investigate the effect of the precursor ratios on the synthetic production, surface chemistry, and photovoltaic performance of CsPbI3 QDs is explored. It is revealed that a decreased Pb/Cs feeding ratio can largely increase the reaction yield, whereas a reduced Pb/I ratio can improve the surface termination and optical properties of the resultaning CsPbI3 QDs. After rational tuning of the synthetic protocol, the reaction yield can be improved more than 7.5 times and the material cost can be reduced from 303 $ g−1 to as low as 42 $ g−1 compared to the conventional binary‐precursor method. In addition, the photovoltaic device using these QDs exhibits an efficiency close to the reported state‐of‐the‐art ones. It is believed that this scalable and low‐cost preparation of CsPbI3 QDs provides new insight into the future commercialization of perovskite QDs‐based optoelectronics.

No abstract