Transparent p-Type Semiconductors: Copper-Based Oxides and Oxychalcogenides

Zhang, Nengduo; Sun, Jian; Gong, Hao

doi:10.3390/coatings9020137

Cited by 67 publications

(53 citation statements)

References 219 publications

(357 reference statements)

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“…because of its low materials cost, abundance of its component elements, and uniquely straightforward manufacturing process [6,7]. It has recently received renewed interest as a photovoltaic and photocatalytic material, mainly due to its favorable band-gap energy of 2.17 eV, high hole mobility, and favorable band edge positions [8][9][10][11]. However, the foremost optical transition at the band-gap energy is parity-forbidden, leading to a weak absorption onset, which limits the efficiency of Cu 2 O as a thin-film absorber [12,13].…”

Section: Introductionmentioning

confidence: 99%

Tuning the electronic band gap of Cu2O via transition metal doping for improved photovoltaic applications

Živković

Roldán

Leeuw

2019

Phys. Rev. Materials

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Cu 2 O is a widely known p-type semiconductor with a band-gap value suitable for photovoltaic applications. However, due to its parity-forbidden nature of the first interband transition and high carrier recombination currents, Cu 2 O has failed to reach commercial application. Hybrid density functional theory has been used to study the effect of transition metal dopants on the electronic and optical properties of Cu 2 O. Substitutional transition metal dopants, incorporated on the copper site, allow band-gap tunability by creating a range of defect states in the electronic structure, from shallow levels to deep intermediate bands. The preferred position of the dopants is in the vicinity of copper vacancies, which are naturally found in Cu 2 O and are responsible for its p-type conductivity. Impurity levels created via extrinsic transition metal dopants increase substantially the capacity of Cu 2 O to absorb light, reaching values close to 10%. First row transition metal dopants thus show potential for considerable improvement of the overall photovoltaic performance of Cu 2 O.

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Section: Introductionmentioning

confidence: 99%

Tuning the electronic band gap of Cu2O via transition metal doping for improved photovoltaic applications

Živković

Roldán

Leeuw

2019

Phys. Rev. Materials

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“…In this case, both E C and E V are within the range of typical metal's work-function energy, so it seems that it can be used for both n-channel and p-channel TFTs' channel material. However, due to its material nature (e.g., high vacancy formation enthalpy, high degree of disorder near E C ), oxygen interstitials and copper vacancies contribute to a p-type conductivity, thus making it a p-type material [17,18].…”

Section: N-type Inorganic Materialsmentioning

confidence: 99%

A Fundamental Reason for the Need of Two Different Semiconductor Technologies for Complementary Thin-Film Transistor Operations

Jang

Lee

2019

Crystals

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In this short commentary, we discuss a fundamental reason why two different semiconductor technologies are needed for complementary thin-film transistor (TFT) operations. It is mainly related to an energy-level matching between the band edge of the semiconductor and the work-function energy of the metal, which is used for the source and drain electrodes. The reference energy level is determined by the energy range of work-functions of typical metals for the source and drain electrodes. With the exception of silicon, both the conduction band edge (EC) and valence band edge (EV) of a single organic or inorganic material are unlikely to match the metal work-function energy whose range is typically from –4 to –6 eV. For example, typical inorganic materials, e.g., Zn–O, have the EC of around –4.5 eV (i.e., electron affinity), so the conduction band edge is within the range of the metal work-function energy, suggesting its suitability for n-channel TFTs. On the other hand, p-type inorganic materials, such as Cu–O, have an EV of around –5.5 eV, so the valence band edge is aligned with metal work-function energy, thus the usage for p-channel TFTs. In the case of p-type and n-type organic materials, their highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) should be aligned with metal work-function energy. For example, p-type organic material, e.g., pentacene, has a HOMO level around –5 eV, which is within the range of the metal work-function energy, implying usage for p-channel TFTs. However, its LUMO level is around –3 eV, not being aligned with the metals’ work-function energy. So it is hard to use pentacene for n-channel TFTs. Along with this, n-type organic materials (e.g., C60) should have HOMO levels within the typical metals’ work-function energy for the usage of n-channel TFT. To support this, we provide a qualitative and comparative study on electronic material properties, such as the electron affinity and band-gap of representative organic and inorganic materials, and the work-function energy of typical metals.

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“…For obtaining SrCu 2 O 2 transparent conducting oxides, several methods of preparation were used. Among the physical methods of SrCu 2 O 2 synthesis, the pulsed laser deposition was mainly approached [5][6][7][8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Comparative study of the thermal behavior of Sr–Cu–O gels obtained by sol–gel and microwave-assisted sol–gel method

Predoană

Atkinson

Karaj

et al. 2020

J Therm Anal Calorim

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In the literature data, several papers reported the synthesis by various chemical or physical methods of the SrCu 2 O 2 (SCO) having possible applications in thermoelectric or completely electronic devices such as solar cells, liquid crystal displays and touch screen. A great challenge is represented by the formation of the pure SrCu 2 O 2 (SCO), due to the high labiality of the Cu valence, depending on temperature. In the present paper, the thermal behavior of Sr-Cu-O gels obtained by sol-gel (SG) or microwave (MW)-assisted SG methods was studied in order to establish the appropriate thermal conditions for pure nanostructured SrCu 2 O 2 preparation. As reagents, copper and strontium acetylacetonate in alcoholic media were used. The starting solutions were homogenized either by stirring for 2 h at room temperature or were exposed to MW for 5 min at 300 W and a frequency of 2.45 GHz. Both solutions were left to gel at room temperature. The obtained gels were investigated by scanning electron microscopy, Fourier-transform infrared spectroscopy, as well as by thermal analysis combined with evolved gas analysis (TG/DTA-MS) measurements in air, inert and reducing atmospheres. For both type of samples, a stepwise thermal decomposition of the gels was noticed in a large temperature range. In the case of samples obtained by microwave-assisted SG method, a higher number of thermal effects were registered assigned to a higher number of molecular species formed in the sample. The residues obtained by non-isothermal treatment up to 900 °C, of both type of samples, were investigated by X-ray diffraction. The results demonstrate the influence of the MW on the SG synthesis and on the thermal properties of the resulted gels. Based on the obtained results, the required thermal treatment of the gels in order to obtain convenient precursors powders for obtaining pure SrCu 2 O 2 could be proposed.

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Transparent p-Type Semiconductors: Copper-Based Oxides and Oxychalcogenides

Cited by 67 publications

References 219 publications

Tuning the electronic band gap of Cu2O via transition metal doping for improved photovoltaic applications

Tuning the electronic band gap of Cu2O via transition metal doping for improved photovoltaic applications

A Fundamental Reason for the Need of Two Different Semiconductor Technologies for Complementary Thin-Film Transistor Operations

Comparative study of the thermal behavior of Sr–Cu–O gels obtained by sol–gel and microwave-assisted sol–gel method

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