Abstract
Solar cells employing hybrid perovskites have proven to be a serious contender versus established thin-film photovoltaic technologies. Typically, current photovoltaic devices are built up layer by layer from a transparent substrate (bottom-up approach), while the deposition of the perovskite layer itself comes with many challenges including the control of crystal size, nucleation density and growth rate. On the other hand, single crystals have been used with great success for studying the fundamental properties of this new class of optoelectronic materials. However, optoelectronic devices fabricated from single crystals often employ different materials than in their thin film counterparts. Here, we demonstrate various top-down approaches for low-temperature processed organic-inorganic metal halide perovskite single crystal devices. Our approach uses common and well-established material combinations that are often used in polycrystalline thin film devices. The use of a polymer bezel allows easier processing of small crystals and the fabrication of solution-processed, free-standing perovskite single crystal devices. All in all these approaches can supplement other measurements of more fundamental material properties often requiring perovskite single crystals by rendering a photovoltaic characterization possible on the very same crystal with comparable material combinations as in thin film devices.
Highlights
Organic-inorganic metal halide perovskites have undoubtedly revolutionized the field of solution-processable optoelectronics[1,2]
Perovskite single crystals, more precisely CH3NH3PbI3 (MAPI) and CH3NH3PbBr3 (MAPB), were synthesized following the inverse temperature crystallization (ITC) approach first demonstrated by Bakr and coworkers[16,22]
The surface of single crystals is known to be the source of defects and degradation and there are indications that structural and optoelectronic properties are remarkably different from the bulk
Summary
Organic-inorganic metal halide perovskites have undoubtedly revolutionized the field of solution-processable optoelectronics[1,2]. A remarkable result that proves the high potential of single crystal perovskite solar cells, many investigations of fundamental properties require free-standing single crystals To test their functionality in a photovoltaic device one would have to incorporate ready-made single crystals into a solar cell stack with selective charge transport layers. To achieve this aim, we follow a top-down approach, i.e. treating ready-made perovskite single crystals in a way so that they can be used in typical solution-processed perovskite solar cell architectures. Separating crystal growth and device built-up makes the approaches presented here more universal and applicable for new developments in crystal synthesis
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