Abstract: Systems and methods for upconversion based on bulk semiconductor sensitizers are provided. In some aspects, issues with previous upconversion approaches are overcome using bulk-semiconductor thin films as sensitizers for the triplet state to achieve efficient upconversion based on triplet-triplet annihilation. Varying the film thickness shifts the threshold of efficient upconversion to subsolar incident powers, enabling practical applications for solar energy harvesting. Systems and methods are provided for upconversion of light in a solid state electronic device, the methods including exposing a bulk semiconductor to a first light source comprising light of a first wavelength, wherein the bulk semiconductor is associated with an organic material capable of upconversion via triplet-triplet annihilation from triplet states in the organic material; and observing light emitted from the organic material at a second wavelength, wherein the second wavelength is shorter than the first wavelength.

Abstract: Embodiments related to systems and methods of crack detection in wafers (e.g., silicon wafers for photovoltaics, photovoltaic devices including silicon wafers) are disclosed. In some embodiments, an apparatus may include a light source configured to illuminate a side of a wafer and a camera directed towards a first face of the wafer. In some embodiments, a long axis of a field of view of the camera may be angled relative to a propagation direction of the light source. In some embodiments, at least a portion of the field of view of the camera is offset from the path of propagation of light emitted from the light source through the wafer. In some embodiments, at least a portion of a light beam may be oriented at a positive non-zero angle relative to the first face of the wafer, and a dimension of the light beam normal to the first face of the wafer may be larger than a thickness of the wafer.

Abstract: Embodiments related to systems and methods of crack detection in wafers (e.g., silicon wafers for photovoltaics, photovoltaic devices including silicon wafers) are disclosed. In some embodiments, an apparatus may include a light source configured to illuminate a side of a wafer and a camera directed towards a first face of the wafer. In some embodiments, a long axis of a field of view of the camera may be angled relative to a propagation direction of the light source. In some embodiments, at least a portion of the field of view of the camera is offset from the path of propagation of light emitted from the light source through the wafer. In some embodiments, at least a portion of a light beam may be oriented at a positive non-zero angle relative to the first face of the wafer, and a dimension of the light beam normal to the first face of the wafer may be larger than a thickness of the wafer.