Abstract
Over the past couple of decades, extensive research has been conducted on silicon (Si) based solar cells, whose power conversion efficiency (PCE) still has limitations because of a mismatched solar spectrum. Recently, a down-shifting effect has provided a new way to improve cell performances by converting ultraviolet (UV) photons to visible light. In this work, caesium lead bromide perovskite quantum dots (CsPbBr3 QDs) are synthesized with a uniform size of 10 nm. Exhibiting strong absorption of near UV light and intense photoluminescence (PL) peak at 515 nm, CsPbBr3 QDs show a potential application of the down-shifting effect. CsPbBr3 QDs/multicrystalline silicon (mc-Si) hybrid structured solar cells are fabricated and systematically studied. Compared with mc-Si solar cells, CsPbBr3 QDs/mc-Si solar cells have obvious improvement in external quantum efficiency (EQE) within the wavelength ranges of both 300 to 500 nm and 700 to 1100 nm, which can be attributed to the down-shifting effect and the anti-reflection property of CsPbBr3 QDs through the formation of CsPbBr3 QDs/mc-Si structures. Furthermore, a detailed discussion of contact resistance and interface defects is provided. As a result, the coated CsPbBr3 QDs are optimized to be two layers and the solar cell exhibits a highest PCE of 14.52%.
Highlights
For the past few years, silicon (Si) based solar cells have become the most commonly-used materials of photovoltaic devices because of its abundant and non-polluting properties with a mature production process [1,2,3]
The quantum confinement effect of CsPbBr3 quantum dots (QDs) is expectable since their mean size approaches the Bohr diameter (7 nm) that was predicted by the Wannier-Mott excitons of bulk CsPbBr3 perovskites [35]
transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurements reveal that cubic CsPbBr3 QDs are formed with an average size of 10 nm
Summary
For the past few years, silicon (Si) based solar cells have become the most commonly-used materials of photovoltaic devices because of its abundant and non-polluting properties with a mature production process [1,2,3]. By virtue of its high efficiency and low cost, multicrystalline Si (mc-Si) solar cells are produced most extensively among various solar cells [4]. Crystalline Si solar cells are limited in power conversion efficiency (PCE), as high-energy photons cannot fully be utilized and photons whose energy is inferior to the bandgap of Si have transmission loss [5]. Pi et al fabricated Si QDs on the surface of mc-Si solar cells via the inkjet printing method and found that solar cell exhibited a relative rise of 2% in PCE because of better spectral response within a short wavelength range of 300 nm to 400 nm [14]. Si QDs fail to achieve high PL quantum yield (QY) due to their indirect Si bandgap [16,17,18]
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