Air-Stable Transparent Silver Iodide–Copper Iodide Heterojunction Diode

Abstract

Transparent AgI-CuI heterojunctions with high rectifying diode behavior were prepared via vapor-phase iodization of metal thin films on transparent conducting oxide substrates. At room temperature, Ag and Cu metal thin films were quickly transformed into the transparent and well-crystallized β-phase of AgI and the γ-phase of CuI, respectively. The AgI and CuI films exhibited n-type and p-type semiconductor properties, respectively, with wide band gaps. The heterojunctions were obtained by applying the CuI film to the AgI film in a sequential iodization process. AgI compounds generally have poor air-stability under light, making them suboptimal for use in electronic applications. Here, we used a CuI top layer to inhibit the photodecomposition of the AgI bottom layer, resulting in an air-stable and smooth AgI-CuI film. We also propose a simple patterning method for the AgI-CuI layer using selective decomposition of AgI without the need for lithography equipment or toxic chemicals. Although there is metal ion exchange between the two layers, each layer has a different chemical composition and crystal structure; therefore, the AgI-CuI heterojunction exhibits pn-diode behavior with a rectifying ratio of 9.4 × 10, which is comparable to that of other transparent pn-diodes. These findings open a new path for electronic application of AgI materials.

Introduction of TiO2 in CuI for Its Improved Performance as a p-Type Transparent Conductor

“…Further, it is well known that the electronic and optical properties of CuI can degrade significantly when stored in ambient condition for long durations. 24,[32][33]36 Therefore, we monitor the optical only improves its optical transparency and holes conductivity but also increases its stability in ambient condition.…”

“…[13][14][15][16] Furthermore, CuI can be synthesized and heavily doped at low temperatures (<100 o C) to achieve a hole conductivity of σ > 280 S/cm while maintaining a transparency of more than 70%. [14][15]17 Owing to aforementioned qualities, CuI has been used to achieve high solar cell efficiencies, [18][19][20][21][22] high rectification ratio diodes (rectification ratios larger than 10 9 ), [23][24] photodetectors, 25 piezoelectric enhancement, 26 flexible transparent thin film transistors (TFTs), 27 and light emitting diodes [28][29] . In addition, CuI has most recently been used as a transparent thermoelectric material to achieve a large thermoelectric figure of merit of ZT=0.21 at 300 C, which is three orders of magnitude higher compared with state-ofthe-art p-type transparent materials.…”

Engineering Copper Iodide (CuI) for Multifunctional p‐Type Transparent Semiconductors and Conductors

“…CuI thin films showed great compatibility with various n‐type metal oxide/halide semiconductors (such as, ZnO, BaSnO 3 , a‐IGZO, AgI, and NiI 2 ) to construct transparent p–n hetero/homojunction diodes. [ 38 , 41 , 125 , 136 , 137 , 138 , 139 ] Grundmann and co‐workers fabricated an epitaxial thin‐film heterojunction of p‐CuI/n‐ZnO with a high rectification of up to 2 × 10 9 and a low saturation current density of 5 × 10 −9 A cm −2 ( Figure 8 a ). [ 139 ] The rectification ratio was ≈100 times higher than that of polycrystalline CuI‐based diodes.…”

One-Pot Synthesis of Copper Iodide-Polypyrrole Nanocomposites

“…However, after 24 h, the absorbance of the entire spectrum significantly decreases as a result of precipitation of the produced composites (see Figure 1b, curve 6). 6 5, Table 1) the period of copper sulphate addition to the iodine reaction mixture by route 1 was varied, and the impact of this procedure on the product yield was evaluated.…”

“…Copper iodide (CuI) has a wide application in nonlinear optics [1,2], solar cells development [3], photocatalysis [4], photoluminescention [5], electrophysics [6,7] and conventional analytical chemistry, i.e., mercury detection [8]. Apart from those, CuI is used as a perspective catalyst in a large number of organic synthesis, viz., Heck-types reactions [9,10], Stills-types [11], Ullmann-type routes [12][13][14][15][16][17][18][19] Suzuki-Miyaura and Sonogashira reactions of cross-coupling [20][21][22] and many others [19,[22][23][24][25][26][27].…”