1. Volume 1, Issue 2, Pages 465-480 (August 2019)
Surface-Tension-Controlled Crystallization for High-Quality 2D Perovskite Single Crystals for Ultrahigh Photodetection 
Yucheng Liu, Haochen Ye, Yunxia Zhang, Kui Zhao, Zhou Yang, Yongbo Yuan, Haodi Wu, Guangtao Zhao, Zupei Yang, Jiang Tang, Zhuo Xu, Shengzhong (Frank) Liu 
Matter 
Volume 1, Issue 2, Pages (August 2019)
DOI: /j.matt
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2. Matter 2019 1, DOI: ( /j.matt )
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3. Figure 1 Crystallization of (PEA)2PbI4 PSCs
(A) The Gibbs free energy change ΔGtotal as a function of particle radius. ΔGtotal consists of a surface term ΔGs and a bulk term ΔGb.
(B) Graph illustrating the lower nucleation barrier for the solution surface compared with that in the solution volume.
(C) Schematic of the single crystal staying afloat on the solution surface.
(D) Schematic of surface tension-controlled crystallization process.
(E) Photographs of the (PEA)2PbI4 PSCs grown at different temperatures.
(F) Corresponding photographs of (PEA)2PbI4 PSCs completed at different temperatures.
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4. Figure 2 Structural Characterizations of (PEA)2PbI4 PSCs
(A) Photograph of a well-shaped 36 × 6 × 6-mm3 bulk 2D (PEA)2PbI4 PSC.
(B) XRD patterns of a 2D (PEA)2PbI4 PSC recorded from (001) and (010) planes.
(C and D) Optimized crystal structures on (001) (C) and (010) (D) facets of (PEA)2PbI4.
(E and F) SEM images of a (PEA)2PbI4 PSC for the (001) (E) and (010) (F) planes.
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5. Figure 3 Optical and Trap-Density Characterizations of (PEA)2PbI4 PSCs
(A) Absorption spectrum (red circles) of the (PEA)2PbI4 PSC. The contribution from excitonic (green line) and continuum band (blue line) transitions are also plotted.
(B) Photoluminescence (PL) of (001) and (010) plane of a (PEA)2PbI4 PSC.
(C) Calculated electronic band structure and density of states of (PEA)2PbI4 without and with account of SOC.
(D) Time-resolved PL (TRPL) spectra of (001) and (010) planes of a (PEA)2PbI4 PSC.
(E) Frequency-dependent capacitance and dielectric constant curve for the (PEA)2PbI4 PSC.
(F) Dark I-V plot of hole-only device used for the trap-state-density measurement.
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6. Figure 4 Anisotropic Transport Properties of (PEA)2PbI4 PSCs
(A) SEM image of the (001) and (010) planes of a (PEA)2PbI4 PSC.
(B and C) Planar device structures fabricated on the (001) (B) and (010) (C) planes of a 2D (PEA)2PbI4 PSC.
(D) Bias-dependent photocurrent of the (PEA)2PbI4 PSC on (001) and (010) planes.
(E) Current-voltage (I-V) curves of the devices made on (001) plane and (010) plane under the same light illumination.
(F–J) Statistics of the measured photocurrent for 20 devices based on (001) and (010) planes of the (PEA)2PbI4 PSC (F). Charge-density distribution corresponding to the CBM (G and I) and the VBM (H and J) for (001) and (010) planes, respectively, of (PEA)2PbI4 PSC.
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7. Figure 5 Photodetection Performance of the (PEA)2PbI4 PSC Devices
(A) Schematic illustration of the working principle and energy-band diagram of the 2D (PEA)2PbI4 PSC photodetector.
(B) I-V curves of the photodetector under dark state and illumination by different light intensities.
(C) Photocurrent versus light intensity of the device under 462-nm light illumination.
(D and E) Light intensity-dependent responsivity (D) and external quantum efficiency (E) of 2D (PEA)2PbI4 PSC photodetector measured at various biases from 1 to 5 V.
(F) Measured dark noise current at various frequencies of the 2D (PEA)2PbI4 and 3D MAPbI3 perovskite single-crystal photodetector. The instrument noise floor, calculated shot noise, and thermal noise limit are also included for reference.
(G) Light intensity-dependent detectivity of 2D (PEA)2PbI4 PSC photodetector measured at various biases from 1 to 5 V.
(H) Detectivity comparison of the photodetectors based on the literature and present work.
(I) Plots of photocurrent density and responsivity of the 2D (PEA)2PbI4 photodetector as a function of light wavelength.
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8. Figure 6 Response Speed and Stability Test of (PEA)2PbI4 PSC Devices
(A) Temporal response of the 2D (PEA)2PbI4 PSC photodetector.
(B) Comparison of the response time of the present 2D (PEA)2PbI4 PSC photodetector with literature-reported photodetectors.
(C) Frequency response of the 2D (PEA)2PbI4 PSC photodetector, showing the −3-dB cutoff frequency of ∼11 kHz.
(D) XRD patterns of 2D (PEA)2PbI4 PSC before and after continuous exposure to 460-nm LED light for 24 h.
(E) Long-term photostability measurement of the 2D (PEA)2PbI4 PSC photodetector. Inset shows photoswitching behavior (2,530 ON/OFF cycles) of the (PEA)2PbI4 PSC photodetector.
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