SEM images of a filter paper before (a),(c), and after (b),(d) quantum dot (QD) dip-casting. (a),(b) Surface images and (c),(d) cross-sectional images with EDX line scan analysis. After QD dip-casting, smooth surface (b) and QD impregnated internal structure (d) are formed. (Reprinted with permission by American Chemical Society)
The researchers demonstrate that paper thermoelectric materials can be fabricated using facile solution-processing and modules can be constructed by cutting p- and n-type paper strips into size and connecting them electrically in series and thermally in parallel without the use of any special equipment.
This is in contrast to traditional bulk thermoelectrics that require time- and energy-intensive processing.
To date, colloidal quantum dots have only been studied as a solution-processed material to deposit uniform thin-films on smooth substrate surfaces such as a silicon wafer or a glass substrate.
"In our study, we adopt a new point of view and utilize colloidal quantum dots as 'impregnating solution'" explains Ko. "Upon dip-casting a blank paper into a colloidal quantum dot solution, quantum dots permeate throughout the entire thickness of the paper and transform it into a semiconducting nanocomposite."