Date Published: March 06, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Jiachen Sun, Jiang Wu, Xin Tong, Feng Lin, Yanan Wang, Zhiming M. Wang.
Investigations of organic–inorganic metal halide perovskite materials have attracted extensive attention due to their excellent properties including bandgap tunability, long charge diffusion length, and outstanding optoelectronic merits. Organic–inorganic metal halide perovskites are demonstrated to be promising materials in a variety of optoelectronic applications including photodetection, energy harvesting, and light‐emitting devices. As perovskite solar cells are well studied in literature, here, the recent developments of organic–inorganic metal halide perovskite materials in optoelectronic devices beyond solar cells are summarized. The preparation of organic–inorganic metal halide perovskite films is introduced. Applications of organic–inorganic metal halide perovskite materials in light‐emitting diodes, photodetectors, and lasers are then highlighted. Finally, the recent advances in these optoelectronic applications based on organic–inorganic metal halide materials are summarized and the future perspectives are discussed.
The exploration of organic–inorganic metal halide perovskite materials has been lasted for half century before they have been intensively researched in recent years. Initially, a perovskite material is only referred to as a calcium titanium oxide mineral (CaTiO3). Later, the perovskite also represents materials with the same crystal structure with CaTiO3. The typical organic–inorganic metal halide perovskite materials can be described as ABX3 in which A represents an organic cation, B is a metal cation, and X represents a halide anion such as I−, Cl−, and Br−. In this structure, A cations are surrounded by [BX6]4− octahedral, as shown in Figure1.1 Such organic–inorganic hybrid perovskites have been well studied for decades. At the turn of the century, there were many researches focusing on their crystal structures,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17 optical properties,3, 7, 8, 11, 12, 13, 15, 18, 19, 20, 21 thermal properties,3, 12, 22 and ferroelectric properties.6, 23, 24, 25, 26 It is shown that the organic–inorganic hybrid perovskite materials possess merits in magnetism,27, 28 ferroelectricity, 2D conductivity, and optoelectronics. In order to understand the fundamental properties of these materials, many characterization methods have been applied, which in turn has led to fabrication of these materials into devices. Schmid and co‐workers fabricated an organic–inorganic perovskite light emitting diode (LED) and achieved an external quantum efficiency of 4%.29 Later, Mitzi and co‐workers also developed an organic–inorganic perovskite field effect transistor (FET) and found that organic–inorganic hybrid materials were very promising to be a channel material,10 which introduced a way for further application of electronic devices.
To fabricate high performance optoelectronic devices based on organic–inorganic hybrid perovskites, it is very important to deposit such absorber layers into a uniform film with full coverage in a controlled manner. It has been widely agreed that the device performance is highly dependent on the fabrication process of perovskites. Several methods have been developed for the deposition of organic–inorganic halide perovskite thin films.44, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75
The organic electroluminescence materials were discovered by Pope et al. in 1960s.88 In 1990s, with the achievement of the conjugated polymer‐based LEDs and the fabrication of flexible LEDs by Gustafsson et al., it has appealed the new idea for the application of organic LED (OLED).89 At present, OLED was regarded as a promising display technology. As OLEDs have many advantages such as integrated, wide‐gamut, full‐color displays, the OLED technology is believed to have potential to replace the liquid crystal display in the future. At the same time, the organic–inorganic hybrid perovskite materials can provide a new chance for develop another efficiency LEDs devices.
Since the first invention of ruby‐laser (Cr:Al2O3) by Maiman in 196095 and later neodymium‐doped yttrium aluminium garnet (Nd:YAG) lasers in 1970s, solid‐state lasers have become a key technology for communication, materials fabrication, medical care, and optical imaging processing. To date, a rich variety of materials have been applied in lasers with emission from the ultraviolet to near‐infrared region such as ZnO, GaN, CdS, and GaAs.96
Photodetectors are important optoelectronic devices for imaging, communication, automatic control, and biomedical sensing. The organic–inorganic hybrid perovskite materials have potential abilities to sense the spectra from visible to NIR, and even to X‐ray, which is very competitive to other material systems for photodetectors. Organic–inorganic hybrid perovskite photodetectors are mainly fabricated by solution processing methods60, 61, 62, 113, 114, 115, 116 owing to its low cost and suitability for room temperature processing. These features are very crucial for the fabrication of flexible photodetectors. Normally, organic–inorganic hybrid perovskite photodetectors are fabricated in a photoconductor, photodiode, or phototransistor structure.117, 118, 119, 120, 121, 122, 123, 124, 125
Besides the huge success in solar cells, organic–inorganic hybrid perovskite materials have also obtained a tremendous attention in the application of alternative optoelectronic devices such as LEDs, lasers, and photodetectors.
The authors declare no conflict of interest.