A multilayer printed circuit board (PCB) can be fabricated using commercially available printing paper, which shows comparable functionalities with the conventional organic PCBs but 100 times lower environmental impact.

properties, low cost, facile preparation and high defect tolerance. [1] Remarkable progress has been made, especially in terms of widespread applications spanning from solar cells, photodetectors, photocatalysts, and solid-state lasers to light-emitting diodes (LEDs). [2] In more recent years, owing to the exceptional luminescence properties, such as high brightness, color tunability, and intense absorption coefficient, lead halide perovskites have found promising potential applications as color converter for next-generation solid-state lightings and backlight displays. [3] Unfortunately, the intrinsic nature of poor stability and toxicity of lead halide perovskites are some serious issues to be tackled if the materials are to be used on a large scale. The chemical instability will severely restrict the lifespan of devices, and the accumulation of lead will cause serious environmental problems and fatal threat to human health. [4] Extensive efforts have been devoted to overcome the thorny challenges on the way to practical applications. To completely eliminate the potential danger of lead leakage, the simplest and practicable way is to replace it in the B site of ABX 3 with nontoxic isovalent metal ions. [5] As reasonable candidates, Ge 2+ and Sn 2+ ions are the first to come to mind for the substitution of Pb 2+ due to the same electronic configuration of ns 2 np 0 Lead halide perovskites have emerged as superstar semiconductors owing to their superior optoelectronic properties. However, the issues of chemical and thermodynamic instability and toxicity are yet to be resolved. Here, the non-and Bi 3+-doped all-inorganic lead-free perovskite derivatives are reported. Most remarkable is the successful extending of excitation of Cs 2 ZrCl 6 to match with the commercial near ultraviolet light-emitting diode chips via deliberate Bi 3+ aliovalent doping. The blue emission, contrary to self-trapped exciton (STE) emissions amply reported previously, originates from Bi 3+ ionoluminescence with a high photoluminescence quantum efficiency of 50%. The competition for harvesting electrons between STEs and Bi 3+ is studied in detail by steady-and transient-state fluorescence spectroscopy in combination with theoretical calculations. Surface grafting endows Cs 2 ZrCl 6 :Bi 3+ with a robust water-resistant core-shell-like structure and abiding emission. Surprisingly, the emission intensity even increases to 115.94% of the initial level after immersing in water for 2 h. The as-obtained phosphor enables the fabrication of a white light-emitting diode (w-LED), achieving CCT = 4179 K and Ra = 81.9. This work not only promotes the step toward development of leadfree, stable, and high-efficiency perovskite derivatives for the next-generation warm w-LEDs, but also reveals the structure-PL relationship.

To meet the rapidly growing demand, it is necessary to develop novel flexible energy storage devices with a high energy density in a limited area, a fast charging ability, a low cost for mass production and a miniaturized device size. To address the above issues, here we introduce the co-electro-deposition strategy, which is able to prepare an electrode material with a high areal capacitance (1670 mF cm À2 at 0.5 mA cm À2 ), a high areal mass (8.5 mg cm À2 ), an excellent mechanical robustness, a high through-put and great convenience even on a piece of a ubiquitous stainless steel mesh current collector. Based on this advancement, we are able to obtain an ultrathin (less than 200 mm) aqueous asymmetric supercapacitor device with a high energy density (1.8 Â 10 À3 W h cm À3 ), a high power density (0.38 W cm À3 at 3.62 Â 10 À4 W h cm À3 ) and an excellent rate capability. This energy storage device is integrated into a prototype smart card to drive a light emitting diode (LED) indicator, which is charged for 5 seconds and can light up the indicator for more than 2 hours, demonstrating great promise in miniaturized novel flexible energy storage devices.