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This study investigates the band alignment of the Zn0.8Mg0.2O/Sb2Se3 interface structure to improve solar cell performance. Sb2Se3 is a promising absorber material. However, Sb2Se3 solar cells exhibit a lower conversion efficiency than CuInGaSe2 and CdTe solar cells. The lower efficiency of Sb2Se3 solar cells is attributed to the severe open‐circuit voltage loss caused by the band structure at the buffer/Sb2Se3 interface. Sb2Se3 solar cells typically employ CdS as the buffer layer, and the CdS/Sb2Se3 interface exhibits a cliff structure, which results in interfacial recombination. By contrast, a ZnMgO buffer layer can form a spike structure with Sb2Se3 at their interface, which reduces recombination and, as a result, enhances conversion efficiency. Therefore, this study employs the ZnMgO buffer layer and analyzes their material properties with various Mg contents and band structure at buffer/absorber layer interface. A ZnMgO buffer layer is sputter‐deposited on Sb2Se3. The optical bandgap of ZnMgO is 3.3–3.72 eV, corresponding to an Mg content of 0–0.35 at%. The carrier concentration indicates an appropriate doping level ranging from 1014 to 1016 cm−3. The Zn0.8Mg0.2O/Sb2Se3 interface is characterized via interface‐induced band bending. The Zn0.8Mg0.2O/Sb2Se3 interface exhibits a spike structure with a positive delta conduction band offset of +0.193 eV. [ABSTRACT FROM AUTHOR]

Computational analysis of triple absorber‐based solar cell structure is undertaken. This solar cell device configuration allows better utilization of the incident solar spectrum. Three different absorbers with a band gap in the range 1–1.5 eV are sandwiched between high‐doped p+ and n+ regions in descending order of electron affinity to form an energy‐matched multiple absorber device. A comprehensive analysis of key device parameters influencing performance, including band gap, conduction band alignment, interfacial defects, and thickness, is presented. The optimized triple absorber device shows beyond Shockley–Queisser limit (SQ limit) performance under the constraint of passivated interfaces with defect density below 1013 cm−2. Wide spectrum coverage leads to high short circuit current and an efficiency of 40.3%, which is higher than the SQ limit for single band gap solar cell. [ABSTRACT FROM AUTHOR]

The valence and conduction band offset in FeNiO/CuNiO bilayer film are studied utilizing X‐ray photoelectron spectroscopy and UV–vis spectroscopy. The bilayer film is grown on Si substrate employing ion beam sputtering technique using a mixture of argon and oxygen gases at 25% oxygen partial pressure. From the precise knowledge of the valence band maxima energies and core‐level energy positions in the single‐layer film and the corresponding shifts in the bilayer film, the valence and conduction band offsets are estimated to be 0.8 and 0.3 eV, respectively. From the computed band offset data, a type‐I band alignment is identified at the interface of the grown bilayer film, which facilitates the knowledge of carrier transport mechanism and is highly attractive for the realization of efficient room‐temperature optoelectronic device. [ABSTRACT FROM AUTHOR]

Ternary zinc tin oxide (ZTO) is one of the few environmental compatible buffer materials with the potential of replacing the n-CdS buffer in Cu(In,Ga)Se2 (CIGS) solar cells and other photovoltaic systems once its properties are fully understood and optimized. In this work, ZTO films were grown by atomic layer deposition and were logically characterized with the aim of understanding the correlations between compositional changes and film properties. The ZnO:SnO2 pulse ratio significantly affected the growth rate, crystal structure, morphology, and band gap of the ZTO films. By controlling the Sn/(Sn + Zn) atomic ratio, the optical band gap of the ZTO films was tuned between 3.05 and 3.36 eV. Integrating the ZTO films as buffer layers in CIGS solar cells, we observed that films with Sn concentrations of 9 to 16 at.% yielded photo-conversion efficiency close to 14%, which was very comparable to efficiency attained with the commonly used CdS buffer. Furthermore, using X-ray photoelectron spectroscopy analysis, we correlated the current-voltage behavior of the cells to the conduction band offset at the ZTO/CIGS interface. [ABSTRACT FROM AUTHOR]

A kesterite Cu2ZnSnS4 thin film solar cell with efficiency of over 9% is obtained by utilizing Zn1–xCdxS film as a replacement to traditional CdS buffer layer. Zn1–xCdxS film can optimize the conduction band offset between Cu2ZnSnS4 absorber and buffer, forming a minor positive conduction band alignment, thereby alleviating the recombination significantly and improving the open circuit voltage and fill factor efficiently. [ABSTRACT FROM AUTHOR]

Amorphous Zn-Sn-O (α-ZTO) layers were deposited by RF magnetron sputtering to provide an alternative n-type buffer layer for CuInSe2 solar cells. Electrical properties, such as the carrier density, mobility, and resistivity were adjusted by controlling the Sn/(Sn+Zn) ratio of the α-ZTO layer and by regulating the oxygen partial pressure during sputtering. Valence band discontinuities of α-ZTO/CuInSe2 were determined using photoelectron yield spectroscopy. The band discontinuity at the interface has 'spikes' in the conduction band offset. Further, the short circuit current of a CIGS solar cell that uses an α-ZTO layer was marginally higher compared to one that used a CdS layer. These results represent a step toward developing a safer, cheaper solar cell with higher performance by using an α-ZTO film instead of a traditional CdS film. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

A whole interfacial transition of electrons from conduction bands of n-type material to the acceptor levels of p-type material makes the energy band engineering successful. It tunes intrinsic ZnO UV emission to UV-free and warm white light-emitting diode (W-LED) emission with color coordinates around (0.418, 0.429) at the bias of 8-15.5 V. The W-LED is fabricated based on antimony (Sb) doped p-ZnO nanowire arrays/Si doped n-GaN film heterojunction structure through one-step chemical vapor deposition with quenching process. Element analysis shows that the doping concentration of Sb is ≈1.0%. The I- V test exhibits the formation of p-type ZnO nanowires, and the temperature-dependent photoluminescence measurement down to 4.65 K confirms the formation of deep levels and shallow acceptor levels after Sb-doping. The intrinsic UV emission of ZnO at room temperature is cut off in electroluminescence emission at a bias of 4-15.5 V. The UV-free and warm W-LED have great potential application in green lights program, especially in eye-protected lamp and display since television, computer, smart phone, and mobile digital equipment are widely and heavily used in modern human life, as more than 3000 h per year. [ABSTRACT FROM AUTHOR]

Limited efficiency of Cu2ZnSnS4 (CZTS) solar cells due to high recombination rates at the CZTS–buffer interface calls for alternative buffer materials to enhance the open circuit voltage and, therefore, the device performance. By means of ab‐initio hybrid functional calculations, the authors investigate the interfaces between the p‐type absorber CZTS and the n‐type buffer materials Al2ZnO4, CeO2, or ZnSnO3 to evaluate the band alignment. Strong hole confinement is predicted for the CZTS/Al2ZnO4 and CZTS/ZnSnO3 interfaces. A small conduction band offset of 0.31 eV is obtained for the CZTS/ZnSnO3 interface, indicating that ZnSnO3 should be considered for improving the efficiency of CZTS solar cells. [ABSTRACT FROM AUTHOR]

Limited efficiency of Cu2ZnSnS4 (CZTS) solar cells due to high recombination rates at the CZTS–buffer interface calls for alternative buffer materials to enhance the open circuit voltage and, therefore, the device performance. By means of ab‐initio hybrid functional calculations, the authors investigate the interfaces between the p‐type absorber CZTS and the n‐type buffer materials Al2ZnO4, CeO2, or ZnSnO3 to evaluate the band alignment. Strong hole confinement is predicted for the CZTS/Al2ZnO4 and CZTS/ZnSnO3 interfaces. A small conduction band offset of 0.31 eV is obtained for the CZTS/ZnSnO3 interface, indicating that ZnSnO3 should be considered for improving the efficiency of CZTS solar cells. [ABSTRACT FROM AUTHOR]