Properties and Applications of Copper(I) Thiocyanate Hole‐Transport Interlayers Processed from Different Solvents

Abstract

decades ago, [1] to organic solar cells (OSCs) now able to convert more than 18% of incident solar energy to electricity, [2] and organic field-effect transistors (OFETs) approaching comparable mobility to polycrystalline silicon and metal-oxide FETs. [3] These achievements largely originate from an evolution in organic semiconducting materials, deeper understanding of the associated device physics, and a proliferation of device engineering expertise. One widely applied element of device engineering is the insertion of appropriate interlayers within the device stack, [4] in order to tune interfacial physical and chemical processes and the heterojunction energy structure. [5] Conventionally, interlayers in organic electronic devices are broadly categorized as electron-injection/transport layers (EILs/ETLs) or hole-injection/transport layers (HILs/HTLs), [4] depending on the charge carrier type for which injection and/or transport is facilitated. These injection and transport layers can also serve, importantly, as blocking layers for the opposite sign of charge carrier, [6] avoiding the need for separate charge blocking layers. Both injecting and blocking properties are determined by the energy level alignments between the interlayers and active materials, also taking into account any dipole induced offsets in the vacuum level. [7] In addition, an optical gap larger than

Pressure-Dependent Structural and Band Gap Tuning of Semiconductor Copper(I) Thiocyanate (CuSCN)

“…24 Above 9.5 GPa, the modes at 111, 204, 339, 430, and 748 cm −1 rapidly weaken, simultaneously the intensity of the new C�N stretching mode increases with increasing pressure, while the intensity of the initial C�N mode decreases, indicating the gradual transition from the β phase to the α phase. 24 Upon further compression above 12.1 GPa, neither of the original peaks can be detected and a new wide Raman band around 1400 and 1600 cm −1 appears up to 23.1 GPa (Figure 2c), which indicates the generation of new C�N bonds in the sample. Similar transition has also been observed in the polymerized K 3 Fe(CN) 6 and NaCN due to the pressureinduced polymerization through breaking C�N bonds and creating interlinked C�N bonds.…”

“…Each of the Raman peaks is strong and distinguished before ∼4 GPa. Above 4 GPa, a new peak appeared at 2150 cm –1 , which can be assigned to the CN stretching modes in α-CuSCN, implying the onset of a structural transition (Figure d) . Above 9.5 GPa, the modes at 111, 204, 339, 430, and 748 cm –1 rapidly weaken, simultaneously the intensity of the new CN stretching mode increases with increasing pressure, while the intensity of the initial CN mode decreases, indicating the gradual transition from the β phase to the α phase .…”

“…Above 4 GPa, a new peak appeared at 2150 cm –1 , which can be assigned to the CN stretching modes in α-CuSCN, implying the onset of a structural transition (Figure d) . Above 9.5 GPa, the modes at 111, 204, 339, 430, and 748 cm –1 rapidly weaken, simultaneously the intensity of the new CN stretching mode increases with increasing pressure, while the intensity of the initial CN mode decreases, indicating the gradual transition from the β phase to the α phase . Upon further compression above 12.1 GPa, neither of the original peaks can be detected and a new wide Raman band around 1400 and 1600 cm –1 appears up to 23.1 GPa (Figure c), which indicates the generation of new CN bonds in the sample.…”

Contrasting analog and digital resistive switching memory characteristics in solution-processed copper(i) thiocyanate and its polymer electrolyte-based memristive devices

“…In the highfrequency region, CuSCN shows a single peak at B2173 cm À1 corresponding to the CRN stretching. 24,37 The thin film of the CuSCN layer exhibits peaks of the S-CRN bending vibration, C-S stretching mode, and CRN stretching mode located at 430 cm À1 , 746 cm À1 , and 2173 cm À1 , respectively. These Raman peaks are characteristic of the b-phase of CuSCN.…”

“…Moreover, CuSCN is solution processable with solvents such as diethyl sulfide (DES) and NH 4 OH, producing large-area thin films without cracks or pin-holes. 24 Hence, it has a huge scope for low-cost solution-processable flexible and transient electronic applications. But, despite these advantages, CuSCN as the primary or sole switching material in memristive devices is less explored.…”