Growth Of Large-scale And High-quality Perovskite Single Crystals And Their Optoelectronic Properties

Organic-inorganic lead halide perovskite polycrystalline thin films have seen rapid progress in photovoltaic and optoelectronic applications due to their broadly tunable compositions achieved using simple solution processing approaches,strong light absorption and low-cost raw materials.However,the massive grain boundaries and defects in polycrystalline thin films were demonstrated as the main reasons for the fast decomposition and ion migration,which were also two major factors of low stability and serious hysteresis in perovskite solar cells.Compared to polycrystalline thin films,perovskite single crystals(PSCs)without grain boundaries possess better semiconductor properties,such as longer carrier lifetime and diffusion length,lower trap densities,higher carrier mobilities and extended absorption spectra,and therefore shown significantly enhanced optoelectronic performance.However,there are still many deficiencies in the PSCs.First of all,their size is still small and its quality is not high enough,which limits the further improvement of device performance and application.Secondly,their bulk resistivity is low,which makes the devices exhibit very high dark current.Thirdly,the present PSCs show serious ion migration,especially under high electric field,which dulls response speed,deteriorates signal-to-noise ratio,causes serious baseline drift,corrodes metal electrodes and therefore influences the stability of the devices.Additionally,the reported PSCs are containing a large amount of high toxicity lead(Pb),which critically limiting their application.Therefore,in order to solve the above problems,the crystal growth strategies,reaction mechanism,dissolution-crystallization balance,crystal structural dimensionality design,replacement of toxic lead and photoelectric detection performance of high quality and large size perovskite single crystals are studied as follows:?.By finetuning the nucleation and growth process,a low temperature gradient crystallization(LTGC)method is developed to fabricate high quality three-dimensional(3D)structure perovskite CH3NH3PbBr3 single-crystals with dimension as large as 47×41×14 mm3.The single crystals exhibit excellent optoelectronic properties,including low trap state density,high mobility,long carrier lifetime and diffusion length.The photodetectors made of such crystals exhibit high operation stability,high external quantum efficiency of 13453%,detectivity of 8×1013 Jones and short response time of 15.8?s.?.Developed high quality 3D structured PSCs with large carrier mobility of 81±5 cm2 V-1 s-1,long carrier lifetime of 899±127 ns and ultralow trap state density of 6.2±2.7×109 cm-3.Based on these crystals,a large area(?1300 mm2)imaging assembly composed of 729-pixel-detector array is further constructed and realized excellent imaging.?.Reported an induced peripheral crystallization strategy to prepare large area bendable 2D structure(C6H5C2H4NH3)2PbI4 single-crystalline membrane(SCM)with area exceeding 2500 mm2 and the thinnest reach to 0.6 ?m.These bendable SCMs exhibit ultralow defect density,superior uniformity and long-term stability.The photodetectors made on the superior ultrathin SCM possess high external quantum efficiency of 26530%,responsivity of 98.17 A W-1 and detectivity as high as 1.62×1015 cm Hz1/2 W-1.?.A surface-tension controlled crystallization method was developed to prepare large 2D structure(PEA)2PbI4 PSCs with the largest one reaching 36 mm in length.Furthermore,photodetectors were fabricated on the PSCs to study its anisotropic optoelectronic properties.We found that the photodetectors fabricated on the(001)plane exhibit better photo response.?.We developed an effective strategy to grow superior inch-sized high-quality 0D-structured lead-free(CH3NH3)3Bi2I9 perovskite-like single crystals with extremely low ion migration,high bulk resistivity and brilliant environmental stability.It is found that the X-ray detectors made on these crystals show high sensitivity of 1947?C Gy air-1 cm-2,very low detection limit of 83 nGyair s-1 and response time as short as 23.3 ms.Additionally,the ultralow baseline drift and excellent X-ray response of such X-ray detectors allow us designed and fabricated the first 0D-structured lead-free perovskite-like single crystalline X-ray imaging system.