Influence of Mg content on the band alignment at CdS∕(Zn,Mg)O interfaces

Rao, G. Venkata; Säuberlich, F.; Klein, Andreas

doi:10.1063/1.1995951

Cited by 67 publications

(40 citation statements)

References 18 publications

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“…[26] Recent studies have shown that much of that increase should be in the conduction band, which agrees with the common anion rule. [27] Here we find a nearunity correlation between the V OC and the bandgap of the Zn 1-x Mg x O for values of x up to 0.2, beyond which the operation of the device is affected detrimentally by series resistance. This indicates that nearly all of the band-edge movement takes place in the conduction band, as would be expected for an n-type material such as ZnO.…”

Section: Introductionmentioning

confidence: 88%

Band‐Offset Engineering for Enhanced Open‐Circuit Voltage in Polymer–Oxide Hybrid Solar Cells

Olson

Shaheen

White

et al. 2006

Adv Funct Materials

194

117

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The power conversion efficiency of organic and hybrid solar cells is commonly reduced by a low open‐circuit voltage (VOC). In these cases, the VOC is significantly less than the energy of the lowest energy absorbed photon, divided by the elementary charge q. The low photovoltage originates from characteristically large band offsets between the electron donor and acceptor species. Here a simple method is reported to systematically tune the band offset in a π‐conjugated polymer–metal oxide hybrid donor–acceptor system in order to maximize the VOC. It is demonstrated that substitution of magnesium into a zinc oxide acceptor (ZnMgO) reduces the band offset and results in a substantial increase in the VOC of poly(3‐hexylthiophene) (P3HT)–ZnMgO planar devices. The VOC is seen to increase from 500 mV at x = 0 up to values in excess of 900 mV for x = 0.35. A concomitant increase in overall device efficiency is seen as x is increased from 0 to 0.25, with a maximum power‐conversion efficiency of 0.5 % obtained at x = 0.25, beyond which the efficiency decreases because of increased series resistance in the device. This work provides a new tool for understanding the role of the donor–acceptor band offset in hybrid photovoltaics and for maximizing the photovoltage and power‐conversion efficiency in such devices.

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Section: Introductionmentioning

confidence: 88%

Band‐Offset Engineering for Enhanced Open‐Circuit Voltage in Polymer–Oxide Hybrid Solar Cells

Olson

Shaheen

White

et al. 2006

Adv Funct Materials

194

117

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“…According to the binding energy of ~532 eV it could be attributed either to hydroxide21 but also to a peroxolike surface species. 41,42 Since the high binding energy component is absent for the ITO samples, the latter Apart from binding energy shifts, which will be discussed below, the valence band spectra in Fig. 3 show three noticeable differences: (i) the sample showing the largest binding energies (a) shows emission on the low binding energy side of the valence band maximum at binding energies 2-3 eV.…”

Section: A-thin Film Depositionmentioning

confidence: 99%

Surface states, surface potentials, and segregation at surfaces of tin-dopedIn2O3

et al. 2006

Self Cite

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Surfaces of In 2 O 3 and tin-doped In 2 O 3 (ITO) were investigated using photoelectron spectroscopy. Parts of the measurements were carried out directly after thin film preparation by magnetron sputtering without breaking vacuum. In addition samples were measured during exposure to oxidizing and reducing gases at pressures of up to 100 Pa using synchrotron radiation from the BESSY II storage ring. Reproducible changes of binding energies with temperature and atmosphere are observed, which are attributed to changes of the surface Fermi level position. We present evidence that the Fermi edge emission observed at ITO surfaces is due to metallic surface states rather than to filled conduction band states. The observed variation of the Fermi level position at the ITO surface with experimental conditions is accompanied by a large apparent variation of the core level to valence band maximum binding energy difference as a result of core-hole screening by the free carriers in the surface states. In addition segregation of Sn to the surface is driven by the surface potential gradient. At elevated temperatures the surface Sn concentration reproducibly changes with exposure to different environments and shows a correlation with the Fermi level position.

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“…6 by the black solid line. The dashed (7) 223 (9) 251 (13) (5) 305 (9) 316 (6) 307 (9) 319 (7) 358 (10) (8) 295 (8) 287 (4) 321 (11) 308 (6) 316 (14) 365 (6) 73 (and therefore, DE g ¼ DE c ). According to the literature, the corresponding range of DE c is shaded in Fig.…”

Section: Of E3 and E3mentioning

confidence: 99%

Impact of strain on electronic defects in (Mg,Zn)O thin films

Schmidt

Müller

Wenckstern

et al. 2014

Journal of Applied Physics

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We have investigated the impact of strain on the incorporation and the properties of extended and point defects in (Mg,Zn)O thin films by means of photoluminescence, X-ray diffraction, deep-level transient spectroscopy (DLTS), and deep-level optical spectroscopy. The recombination line Y 2 , previously detected in ZnO thin films grown on an Al-doped ZnO buffer layer and attributed to tensile strain, was exclusively found in (Mg,Zn)O samples being under tensile strain and is absent in relaxed or compressively strained thin films. Furthermore a structural defect E3 0 can be detected via DLTS measurements and is only incorporated in tensile strained samples. Finally it is shown that the omnipresent deep-level E3 in ZnO can only be optically recharged in relaxed ZnO samples.

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Influence of Mg content on the band alignment at CdS∕(Zn,Mg)O interfaces

Cited by 67 publications

References 18 publications

Band‐Offset Engineering for Enhanced Open‐Circuit Voltage in Polymer–Oxide Hybrid Solar Cells

Band‐Offset Engineering for Enhanced Open‐Circuit Voltage in Polymer–Oxide Hybrid Solar Cells

Surface states, surface potentials, and segregation at surfaces of tin-dopedIn2O3

Impact of strain on electronic defects in (Mg,Zn)O thin films

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