High efficiency CdSe quantum-dot sensitized solar cells

High quality CdSe quantum-dot (QD) sensitized solar cells have been successfully fabricated by in-situ deposition of QDs into TiO2 nanoporous electron conductor (EC) films using a near room-temperature solution-based chemical bath deposition (CBD) method. An energy conversion efficiency of 4.44% under AM1.5G illumination is achieved on a device fabricated using CdSe QDs as a light absorber, TiO2 nanoparticles as an electron-conducting film, and a Polysulfide Na2S/S based electrolyte as a hole-conductor. Results also show that incident photo conversion efficiency (IPCE) of above 70% was obtained within a majority of the CdSe QD absorption spectrum range, and a peak value of 83% between 500-550nm. The light harvesting efficiency of the QD in the device is evaluated to between 75-85% in the same spectral range, indicating an internal quantum efficiency of greater than 95% was achieved. These results are among the best reported to date of the QD-based solar cells. We present data from prototype devices of various EC film thicknesses, morphologies, material composites, as well as QD deposition conditions and hole conductor variations and show how they impact key device metrics.