Mitk'El Santiago-Berrios - PbSe Nanocrystal Excitonic Solar Cells

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      Publication Details (including relevant citation   information):

      DOI: 10.1021/nl901930g

      Abstract:

      We report the design, fabrication, and characterization of   colloidal PbSe nanocrystal (NC)-based photovoltaic test   structures that exhibit an excitonic solar cell mechanism. Charge   extraction from the NC active layer is driven by a photoinduced   chemical potential energy gradient at the nanostructured   heterojunction. By minimizing perturbation to PbSe NC energy   levels and thereby gaining insight into the “intrinsic”   photovoltaic properties and charge transfer mechanism of PbSe NC,   we show a direct correlation between interfacial energy level   offsets and photovoltaic device performance. Size dependent PbSe   NC energy levels were determined by cyclic voltammetry and   optical spectroscopy and correlated to photovoltaic measurements.   Photovoltaic test structures were fabricated from PbSe NC films   sandwiched between layers of ZnO nanoparticles and PEDOT:PSS as   electron and hole transporting elements, respectively. The device   current−voltage characteristics suggest a charge separation   mechanism that is distinct from previously reported Schottky   devices and consistent with signatures of excitonic solar cells.   Remarkably, despite the limitation of planar junction structure,   and without film thickness optimization, the best performing   device shows a 1-sun power conversion efficiency of 3.4%, ranking   among the highest performing NC-based solar cells reported to   date.

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