Quasi-Zero Dimensional Halide Perovskite Derivates: Synthesis, Status, and Opportunity

Abstract

In recent decades, many technological advances have been enabled by nanoscale phenomena, giving rise to the field of nanotechnology. In particular, unique optical and electronic phenomena occur on length scales less than 10 nanometres, which enable novel applications. Halide perovskites have been the focus of intense research on their optoelectronic properties and have demonstrated impressive performance in photovoltaic devices and later in other optoelectronic technologies, such as lasers and light-emitting diodes. The most studied crystalline form is the three-dimensional one, but, recently, the exploration of the low-dimensional derivatives has enabled new sub-classes of halide perovskite materials to emerge with distinct properties. In these materials, low-dimensional metal halide structures responsible for the electronic properties are separated and partially insulated from one another by the (typically organic) cations. Confinement occurs on a crystal lattice level, enabling bulk or thin-film materials that retain a degree of low-dimensional character. In particular, quasi-zero dimensional perovskite derivatives are proving to have distinct electronic, absorption, and photoluminescence properties. They are being explored for various technologies beyond photovoltaics (e.g. thermoelectrics, lasing, photodetectors, memristors, capacitors, LEDs). This review brings together the recent literature on these zero-dimensional materials in an interdisciplinary way that can spur applications for these compounds. The synthesis methods, the electrical, optical, and chemical properties, the advances in applications, and the challenges that need to be overcome as candidates for future electronic devices have been covered.

Roadmap on thermoelectricity

“…Since their thermal conductivity is extremely low, they have been investigated also as thermoelectric materials. A ZT of 2 has been predicted, but the maximum demonstrated value is one order of magnitude lower [221]. This ZT value is that one reached by commercial thermoelectric materials at 650 °C [222].…”

“…Additionally, engineering perovskites with high stability (in air, under light and moisture exposure) is of significant importance for thermoelectrics. A possible solution is low-dimensional perovskites that have been shown to exhibit enhanced stability and lower ion migration than their 3D counterparts [221,225,226]. Another market requirement is that tons of self-assembly low dimensional thermoelectric materials should be easily produced.…”

“…Halide perovskite can be straightforwardly sensitised at low temperatures on rigid or flexible substrates to meet the market demand. Moreover, bulk materials with 2D, 1D or 0D characters can be produced (figure 19(b)) [221,227], even if few reports on one-dimensional thin-film have been published (they have been mostly synthesised as large single crystals) [228]. It has to be mentioned that all the compounds not having ABX 3 stoichiometry (where A and B are the organic or inorganic cations, and X is the halide) should be named perovskite derivatives, and often the charge is partially confined so they are called quasi-low dimensional materials [228,229].…”

“…On the other hand, the charge confinement impacts one of the main factors, critical for thermoelectrics: the charge mobility is dramatically reduced. Therefore, low electrical conductivity is the first concern of researchers working in the thermoelectric sector [221].…”

Decisive role of heavy-atom orientation for efficient enhancement of spin–orbit coupling in organic thermally activated delayed fluorescence emitters

“…Hybrid organic emitters bearing cheap and abundant nonmetallic heavy atoms (HAs) attract more and more attention lately. [1][2][3][4] Such materials can be the Golden mean between allorganic materials and heavy-metal complexes or inorganic analogues. Potentially, the rational design of such hybrid materials can preserve the advantages of organic and heavymetal materials to enable fast conversion of electric energy into light in a submicrosecond regime but avoid low efficiency of organics and high cost and environmental issues connected with the use of heavy metals.…”