Optical Properties of ZnO/ZnS and ZnO/ZnTe Heterostructures for Photovoltaic Applications

• Published in: Nano letters 2007-08, Vol.7 (8), p.2377-2382
• Main Authors: Schrier, Joshua, Demchenko, Denis O, Lin-Wang, Alivisatos, A. Paul
• Format: Article
• Language: English
• Subjects: Applied sciences; Computer Simulation; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electric Power Supplies; Electromagnetic Fields; Electron states; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Light; Methods of electronic structure calculations; Models, Chemical; Models, Molecular; Molecular electronics, nanoelectronics; Nanostructures - chemistry; Nanostructures - radiation effects; Nanostructures - ultrastructure; Nanotechnology - methods; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of low-dimensional, mesoscopic, and nanoscale materials and structures; Particle Size; Photochemistry - methods; Physics; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Semiconductors; Tellurium - chemistry; Tellurium - radiation effects; Zinc Oxide - chemistry; Zinc Oxide - radiation effects
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl071027k

Although ZnO and ZnS are abundant, stable, and environmentally benign, their band gap energies (3.44, 3.72 eV, respectively) are too large for optimal photovoltaic efficiency. By using band-corrected pseudopotential density functional theory calculations, we study how the band gap, optical absorption, and carrier localization can be controlled by forming quantum-well-like and nanowire-based heterostructures of ZnO/ZnS and ZnO/ZnTe. In the case of ZnO/ZnS core/shell nanowires, which can be synthesized using existing methods, we obtain a band gap of 2.07 eV, which corresponds to a Shockley−Quiesser efficiency limit of 23%. On the basis of these nanowire results, we propose that ZnO/ZnS core/shell nanowires can be used as photovoltaic devices with organic polymer semiconductors as p-channel contacts.