Thin Film Electrochemical Capacitors Based on Organolead Triiodide Perovskite

Abstract

Current understanding on the ionic properties of organometal halide perovskites mostly relies on studies of perovskite electronic devices, e.g., photoconductors or photovoltaic cells, [ 5 ] where ionic transport is not decoupled from electronic conduction. Yang et al. employed a galvanic cell structure (Pb | MAPbI | AgI| Ag 3 ) to investigate the ion conduction in organolead iodide perovskites. [ 6 ] Interestingly, the work suggests that the ionic conductivity, contributed mainly by diffusion of iodide ions, is higher than the electronic conductivity in MAPbI 3 . However, the transport study was carried on perovskite "pellets" compressed from fi ne powders, rather than perovskite thin fi lms used often in solar cells or light emitting diodes. Very recently Zhang et al. reported an organometal halide perovskite-based light emitting electrochemical cell, which utilizes ionic and electronic conductions together to generate light emission in the perovskite layer. [ 1e ] In this work we integrate perovskite thin fi lms in an electrochemical capacitor (EC) cell confi guration, where direct current electronic conduction through the device is blocked by an ionpermeable membrane. A "poor solvent," 1-butanol, is used as the electrolyte solvent to support ion motion through the membrane. The EC cells show excellent cyclability with stable capacitance output beyond 10 000 cycles. By performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) characterizations on the cells with different electrolytes and perovskite thickness, the specifi c capacitance corresponding to the cell interfaces were extracted, showing that the perovskite layer acts not only as a polarized electrode, but also as a solid electrolyte, where iodine-dominant ion migration occurs. Through circuit modeling of the EIS characteristics, we extracted the density of mobile ions (i.e., ionic native defects) in the perovskite fi lms and found it to be lower than those estimated from perovskite electronic devices. The result suggests that the ion formation and transport processes in organometal halide perovskites are largely activated by fl ow of free charge carriers and may also be interface-dependent. Results and Discussion Device Structure and Film MorphologySchematics of the symmetric EC structure are shown in Figure 1 . In the MAPbI 3 based devices, the two perovskite Organometal halide perovskites exhibit not only extraordinary electronic properties but also interesting ionic responses due to the ease of forming and moving native defects in the perovskite lattice. In this work such dual (electronic and ionic) conduction property is exploited to fabricate a thin fi lm electrochemical capacitor (EC) based on organolead triiodide perovskite. The EC cells show excellent cyclability with stable capacitance output beyond 10 000 cycles. By performing electrochemical characterizations on the cells with different electrolytes and perovskite thickness, it is found that the perovskite layer serves not only as an electrode but also a solid elec...

Low‐Dimensional Perovskites: From Synthesis to Stability in Perovskite Solar Cells

“…Recently, organic-inorganic metal halide perovskites have attracted much interest from the scientific community for various applications, including solar cells, [1][2][3][4][5][6][7][8][9][10][11][12] lasers, [13][14][15] light emitting diodes (LED), [16][17][18] water splitting, [19,20] photodetectors, [21][22][23][24][25] field-effect transistors, [26][27][28][29][30] nonvolatile memory, [31,32] capacitors, [33] battery, [34,35] optical amplifiers, [36] lasing, [37][38][39] and laser cooling. [40] They are now considered the most exceptional materials due to their high efficiency and ease in fabrication, and the materials used to form perovskite are extensively available and inexpensive.…”

Extending lead-free hybrid photovoltaic materials to new structures: thiazolium, aminothiazolium and imidazolium iodobismuthates

“…9) in 2013 to over 22% today, 10 as well as much increased stability under humidity and oxygen. [11][12][13][14] In addition, lead-halide perovskites have also been studied in other devices including capacitors, 15 batteries 16 and the integration of a solar cell and supercapacitor. 17 However, one intrinsic limitation of these perovskite materials is the toxicity of lead, which raises environmental and health concerns and thus hinders future large-scale implementation.…”

Mutual Insight on Ferroelectrics and Hybrid Halide Perovskites: A Platform for Future Multifunctional Energy Conversion

“…Ferroelectrics have a proven potential as a dielectric material in a parallel plate capacitor structure, but there are no reports on hybrid halide perovskites for this application. However, hybrid halide perovskites have been studied as an electrode or an electrolyte in supercapacitors …”

“…Recently, Zhou et al reported a thin‐film electrochemical capacitor (5.89 µF cm −2 ) based on an organo‐lead‐tri‐iodide perovskite which exhibited a stable capacitance beyond 10 5 cycles . Such an approach provides a novel dimension for studying the ionic properties of hybrid halide perovskites and developing new devices.…”