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Research Paper | Material Science | India | Volume 12 Issue 5, May 2023
Synthesis of Near-Infrared Bandgap Lead Sulfide Quantum Dots to Mimic the Solar Spectrum
Abstract: The limiting efficiency for a conventional single junction solar cell is restricted to 32%, known as Shockley?Queisser limit. Commercially successful monocrystalline silicon (c-Si) solar cells reached 26.8%, and emerging perovskite solar cells achieved 25.2% efficiency on a lab scale. Most of the contemporary solar cell technologies and research are focused on replacing silicon with inexpensive materials and processes to reduce the KW/hr cost of solar cells. However, materials used for the development of single-junction solar cells (c-Si, perovskite, organic dyes, and polymers) only harness a part of the solar spectrum, leaving behind a significant unused NIR spectrum (~50% of the solar energy). Utilization of the unused NIR solar radiation in tandem solar cell architecture would lead to significantly higher efficiency (~45% for two junction tandem solar cells). However, the scarcity of desired low bandgap materials is the Achilles? heel for the utilization of NIR photons in solar cells. Though a few III-V class compound semiconductors have the desired NIR band gaps, material scarcity and the requirement of sophisticated processing techniques hinder their large-scale utilization. Herein I showcase the synthesis of NIR bandgap lead sulfide (PbS) quantum dots (QDs) mimicking the solar spectrum. The as-synthesized QDs show an absorption onset of 1350 nm (0.92 eV), which is ideal for the two-junction tandem solar cell development. Optical characterizations of as-synthesized QDs are performed via absorption and emission spectroscopy, and the structural characterizations are carried out by X-ray diffraction (XRD) and transmission electron microscopy (TEM).
Keywords: NIR Bandgap, PbS quantum dots, NIR optoelectronic devices
Edition: Volume 12 Issue 5, May 2023,
Pages: 1325 - 1327