Inhibition of Ion Migration for Reliable Operation of Organolead Halide Perovskite‐Based Metal/Semiconductor/Metal Broadband Photodetectors

Abstract

Organolead halide perovskites (OHPs) have attracted extensive attention as light harvesting materials for solar cells recently, because of their high charge carrier mobility, high photoconversion effi ciencies, low cost, and simple methodology. Despite these advantages, the OHPs exhibit sweep-dependent hysteresis behavior in current-voltage characteristics fi lms, deteriorating the reliability of devices based on the OHPs. This study demonstrates reliable high on/off ratio ( I on / I off = 10 4 ) CH 3 NH 3 PbI 3 broadband photodetectors with buffer layer-free simple metal/semiconductor/metal lateral structure. At high external bias, poor on/off ratios and spikes in dark current and photocurrent are observed due to the migration of charged defect ions. The ion migration can be effectively inhibited at low external bias, and thus the devices show high I on / I off ratios and spike-free dark current and photocurrent. In addition, prevention of the prepoling in the CH 3 NH 3 PbI 3 fi lms by operating at the low external bias results in pronouncedly enhanced signal-to-noise ratios even under low intensity incident light. These results strongly propose that inhibiting the migration of charged defect ions in CH 3 NH 3 PbI 3 fi lms is a key in developing reliable high performance CH 3 NH 3 PbI 3 -based devices.

Temperature-dependence studies of organolead halide perovskite-based metal/semiconductor/metal photodetectors

“…Methylammonium iodide (CH 3 NH 3 I) and lead chloride (PbCl 2 ) were prepared according to previous work. 26 The preheated precursor solution at 70 C was used for fabricating the MAPbI 3Àx Cl x thin lm. Next, the CH 3 NH 3 PbI 3Àx Cl x precursor solution was spin coated onto the treated substrate at a rate of 4000 rpm for 30 s. The wet perovskite lm was then annealed on a hot plate to complete the crystallization.…”

“…Recently, hybrid organic-inorganic lead halide perovskites (CH 3 NH 3 PbX 3 , where X ¼ Cl, Br, and I) have attracted great attention as light absorbers not only for frequently studied solar cells 1-10 but also for (LEDs), [11][12][13] eld-effect transistors (FETs), [14][15][16] lasers, [17][18][19] and photodetectors. [20][21][22][23][24][25][26][27][28][29][30] The perovskites have excellent semiconductor properties, such as a direct band gap, a broad absorption range and high carrier mobility. 23,24 Until now, there are several research works reported on Metal-Semiconductor-Metal (MSM) photodetectors based on Si or GaAs, [31][32][33][34] and several signicant efforts to fabricate high performance CH 3 irradiance power density of 2.12 nW cm À2 , with the highest responsivity of 953 A W À1 and external quantum efficiency of 2.22 Â 10 5 %.…”

“…23,24 Until now, there are several research works reported on Metal-Semiconductor-Metal (MSM) photodetectors based on Si or GaAs, [31][32][33][34] and several signicant efforts to fabricate high performance CH 3 irradiance power density of 2.12 nW cm À2 , with the highest responsivity of 953 A W À1 and external quantum efficiency of 2.22 Â 10 5 %. 24 These high property perovskite photodetectors are prepared with several structures, like Au/perovskites/Au, 24,28 Pt/Ti/perovskites/Pt/Ti, 26 ITO/perovskites/ITO, 27 and the solar cell structures. 25,29 Basic electrical parameters such as on/off ratio, responsivity and detectivity are measured under different illumination intensities 23,24,27 and optical wavelength.…”

“…25,29 Basic electrical parameters such as on/off ratio, responsivity and detectivity are measured under different illumination intensities 23,24,27 and optical wavelength. 26,27 Although so many remarkable efforts have been made to detect the characteristics of photodetectors based on CH 3 NH 3 PbX 3 single crystals under different structures and conditions, polycrystalline perovskites photodetectors are rarely discussed, which should be considered owing to their low preparation cost. In addition, temperature-dependence studies are signicant for the performance and reliability of the photodetectors, which should be focused on by researchers.…”

Single Crystals: The Next Big Wave of Perovskite Optoelectronics

“…5,[141][142] Regarding the lateral structure devices using high-quality perovskite films with a large electrode spacing, a relatively high working voltage is required to maintain a high gain. 124,[143][144][145][146][147][148][149][150][151] Single-crystal perovskite-based photoconductors with low trap density showed ultrahigh responsivities exceeding 103 AW -1 . 4,35,152 The critical components for forming a Schottky junction with asymmetric electrodes are illustrated in Fig.…”