Non-dissipative internal optical filtering with solution-grown perovskite single crystals for full-colour imaging

Herein we demonstrate that solution-grown single crystals of semiconducting methylammonium lead halide perovskites (MAPbX3, where MA=CH3NH3+, X=Cl−, Br− and Br/I−) can be used as semiconductor absorbers for full-colour imaging. A one-pixel photodetector prototype was constructed by stacking three layers of blue-, green- and red-sensitive MAPbCl3, MAPbBr3 and MAPb(Br/I)3 crystals, respectively. The prototype detector was demonstrated to recognize and faithfully reproduce coloured images by recombination of the signals from each individual colour channel. This layered structure concept, besides imparting a two- to three-fold reduction in the number of required pixels, also offers several other advantages over conventional technologies: three times more efficient light utilization (and thus higher sensitivity) than common Bayer scheme devices based on dissipative optical filters, colour moiré suppression and no need for de-mosaic image processing. In addition, the direct band gap structure of perovskites results in optical absorption that is several orders of magnitude greater than silicon. This opens a promising avenue towards the reduction of pixel-size in next-generation devices as compared with conventional silicon-based technologies. The light-capturing efficiencies of full-color sensors could be tripled by switching to tiny pixels made from stacked perovskite crystals. Vertically stacked layers of red-, green-, and blue-detecting silicon pixels convert light into charges more efficiently than the lateral arrangement used in typical digital-camera sensors. They also provide desirable long-pass filtering. Maksym Kovalenko from ETH Zürich in Switzerland and colleagues now report a route to low-cost stacked RGB sensors using solution-grown methylammonium lead halides containing bromide, chloride or iodide ions. The direct band gap of these perovskites gives them sharply defined color absorptions that outperform silicon stacks by several orders of magnitude. Imaging experiments with a single-pixel prototype produced accurate color reproductions at high photoresponse speeds and gave promising prospects for miniaturization onto transistor devices. Solution-grown single crystals (SCs) of semiconducting methylammonium lead halide perovskites are promising materials for full-colour imaging. Here we show one-pixel photodetector prototype, constructed by stacking three layers of blue-, green- and red-sensitive MAPbCl3, MAPbBr3 and MAPb(Br/I)3 crystals, respectively. This layered structure concept has several advantages: imparting a two- to three-fold reduction in the number of required pixels, three times more efficient light utilization (and thus higher sensitivity) than common Bayer filters scheme, colour moiré suppression and no need for de-mosaic image processing. In addition, the direct band gap structure of perovskites results in optical absorption that is several orders of magnitude greater than silicon.