Lead sulfide nanocrystal/conducting polymer solar cells

Abstract

Organic photovoltaics promise a number of key advantages over conventional silicon, namely: Ease of processing, low cost, physical flexibility and large area coverage. However, the solar power conversion efficiencies of pure polymer devices are poor. When nanocrystals are blended with a conducting polymer to create a bulk heterojunction structure the optical and electronic properties of both materials combine synergistically to enhance overall performance. We have investigated the dependence of efficiency on the polymer molecular weight, together with the role of nanocrystals in the photogeneration of charge carriers in bulk heterojunction solar cells. We found that a high molecular weight polymer resulted in the formation of small nanocrystals, and that nanocrystals act to enhance the natural spectral response of the polymer.

Quantum Dot Composite Radiation Detectors

“…Instead of the indirect approach, we chose to pursue a direct-conversion route, which holds the promise of better energy resolution. Our initial effort was inspired by photovoltaic research suggesting the use of organic semiconductors as host materials to quantum dots that sensitized the material to wavelengths of interest (Schwenn et al, 2005). Although these prior efforts were able to produce quantum dot/organic semiconductor films 1 µm thick, such thicknesses would only be appropriate for capturing low-penetration radiation (e.g., visible light or alpha particles).…”

“…where τ lifetime is lifetime for charge carries and τ transition is time needed for charge carries to go across the device thickness d under applied bias voltage V. Mobility-lifetime measurements were obtained using published methods (Schwenn et al, 2005), in response to a fast (250 ns) laser pulse of infrared radiation (900 nm), and to ambient light. Resistivity measurements, measured by recording the leakage current while the detector is in reverse bias in the dark, show that the average value is 3 x 10 10 Ω-cm.…”