Layer-by-Layer Assembly of Sintered CdSexTe1\u2013xNanocrystal Solar Cells

Alloying is a versatile tool for engineering the optical and electronic properties of materials. Here, we explore the use of CdTe and CdSe nanocrystals in developing sintered CdSexTe1x alloys as bandgap tunable, light-absorbing layers for solution-processed solar cells. Using a layer-by-layer approach, we incorporate such alloyed materials into single- and gradedcomposition device architectures. Nanostructured solar cells employing CdSexTe1x layers are found to exhibit a spectral response deeper into the IR region than bulk CdTe devices as a result of optical bowing and achieve power conversion efficiencies as high as 7.1%. The versatility of the layer-by-layer approach is highlighted through the fabrication of compositionally graded solar cells in which the [Se]:[Te] ratio is varied across the device. Each of the individual layers can be clearly resolved through cross-sectional imaging and show limited interdiffusion. Such devices demonstrate the importance of band-alignment in the development of highly efficient, nanostructured solar cells