Junwen Li

Broadband absorption enhancement achieved by optical layer mediated plasmonic solar cell

We propose a novel thin solar cell design, integrating plasmonic component with optical layer, for conspicuous performance improvement in organic (P3HT: PCBM) thin film solar cell. Despite the relatively simple structure, the designed solar cell can get strikingly high spectral performance with the short circuit current density (J(sc)) enhancement up to 67%; and a nicely large J(sc) enhancement over 50% can be easily obtained spanning rather a broad geometric parametric range. The mechanisms responsible for this significant and broadband absorption enhancement as well as the effects of intercalating a plasmonic nanoparticles (NPs) array and an optical layer are theoretically and systematically investigated by finite-difference time-domain calculations (FDTD). The origin of the dramatically increased absorption is believed to be the synergistic effect between 1) the enhanced electric field and forward scattering upon excitation of localized surface plasmon resonance (LSPR) of the NPs, and 2) the favorable redistributions of light field in the device due to the beneficial interference effect mediated by the optical layer. Such a design concept is quite versatile and can be easily extended to other thin film solar cell systems.

Maximizing Integrated Optical and Electrical Properties of a Single ZnO Nanowire through Native Interfacial Doping

A native interfacial doping layer introduced in core-shell type ZnO nano-wires by a simple vapor phase re-growth procedure endows the produced nano-wires with both excellent electrical and optical performances compared to conventional homogeneous ZnO nanowires. The unique Zn-rich interfacial structure in the core-shell nanowires plays a crucial role in the outstanding performances.

Synthesis and Characterization of ZnO Bicrystalline Nanosheets Grown via Ag-Au Alloy Catalyst

ZnO bicrystalline nanosheets have been synthesized by using Agx Au1−x alloy catalyst via the vapor transport and condensation method at 650 °C. High resolution transmission electron microscopy characterization reveals a twin boundary with {01–13} plane existing in the bicrystalline. A series of control experiments show that both AgxAu1−x alloy catalyst and high supersaturation of Zn vapor are prerequisites for the formation of ZnO bicrystalline nanosheet. Moreover, it is found that the density of ZnO bicrytalline nanosheets can be tuned through varying the ratio of Ag to Au in the alloy catalyst. The result demonstrates that new complicated nanostructures can be produced controllably with appropriate alloy catalyst.

Remarkable enhancement of photovoltaic performance of ZnO/CdTe core–shell nanorod array solar cells through interface passivation with a TiO2 layer

All-inorganic solid-state ZnO/CdTe core–shell nanorod array solar cells (NRASCs) have been fabricated by a simple low-temperature and low-cost chemical solution method. A thin TiO2 layer with different thickness was introduced at the ZnO/CdTe interface using atomic layer deposition and its effect on the photovoltaic performance of the NRASCs was investigated. It is found that the overall power conversion efficiency of the ZnO/TiO2 (4 nm)/CdTe NRASC can reach up to 1.44% under AM 1.5G illumination (100 mW cm−2), which is about 6 times of the NRASC without TiO2 layer. By further systematic characterizations, we find that the thin TiO2 layer, serving as an efficient passivation and blocking layer at the interface of ZnO/CdTe nanorod, can remarkably suppress the charge recombination at the interface but negligibly affect the light absorption and the charge separation efficiency, thus leading to significant increases of the carrier lifetime and the open-circuit voltage of the NRASCs. This result expands the knowledge and opportunities for low-cost, high-performance NRASCs through simple interface engineering.