In this work, inverted polymer:fullerene organic photovoltaic (OPV) cells with solution-processed zinc oxide (ZnO) as the electron collecting layer are investigated. ZnO films are prepared simply by the spin-casting of a zinc acetate dehydrate precursor solution, followed by sintering under ambient conditions. The performance of the fabricated inverted OPV cells shows a clear dependence on precursor concentration and sintering conditions. With the ZnO film derived from a sol-gel concentration of 0.1 M and sintered at 350 C for 10 min, the inverted OPV cell shows optimum performance. #

Statistical process control is an important tool to monitor and control a process. It is used to ensure that the manufacturing process operates in the in-control state. Multi-variety and small batch production runs are common in manufacturing environments like flexible manufacturing systems and Just-in-Time systems, which are characterized by a wide variety of mixed products with small volume for each kind of production. It is difficult to apply traditional control charts efficiently and effectively in such environments. The method that control charts are plotted for each individual part is not proper, since the successive state of the manufacturing process cannot be reflected. In this paper, a proper t-chart is proposed for implementation in multi-variety and small batch production runs to monitor the process mean, and its statistical properties are evaluated. The run length distribution of the proposed t-chart has been obtained by modelling the multi-variety process. The ARL performance for various shifts, number of product types, and subgroup sizes has also been obtained. The results show that the t-chart can be successfully implemented to monitor a multi-variety production run. Finally, illustrative examples show that the proposed t-chart is effective in multi-variety and small batch manufacturing environment.

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Self-powered photodetectors (PDs) with inorganic lead halide perovskites hold multiple traits of high sensitivity, fast response, independence from external power supply, and excellent sustainability and stability, thus holding a great promise for practical applications. However, they generally contain high-temperature-processed electron-transporting layers (ETLs) and high-cost, unstable hole-transporting layers (HTLs) coupled with noble metal electrodes, which bring significant obstacles of production cost and stability for their potential commercialization. Herein, we demonstrate the building of high-performance HTL/ETL-free, self-powered CsPbIBr2 PD with simplified architecture of fluorine-doped tin oxide (FTO)/CsPbIBr2/carbon upon interfacial modification by polyethyleneimine (PEI). The optimized PD yields a dark current of 2.03 × 10–9 A, peak responsivity (R) of 0.32 A/W, maximum specific detectivity (D*) of 3.74 × 1012 Jones, and response time of 1.21 μs. These figures of merit are far beyond those of the one prepared without PEI modification and even the PD containing TiO2 ETL. Hence, our work suggests a highly feasible route to develop self-powered PDs with significantly simplified fabrication and a reduced production cost.

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