Doping of specific boron species in carbon frameworks plays an important role in enhancing the electrochemical properties of carbon. Herein, we prepared a tailored boron species-doped carbon nanotube (CNT) catalyst as the counter electrode (CE) of quantum dot sensitized solar cells (QDSSCs) by hydrothermal post-treatment of pre-oxidized CNTs. X-ray photoemission spectroscopy results show that boron is mainly present as oxygen-containing (C–O–B) and oxygen-free (C–B) boron in the sp2 carbon framework, so different levels of pre-oxidation treatments can control the content of oxygen-containing boron species and thus achieve controlled doping of boron species. Electrochemical impedance spectroscopy shows that the optimized boron-doped CNTs (BCNT1) obtained a charge transfer resistance (Rct) as low as 2.17 Ω, indicating excellent reduction activity to Sn2− at the CE/electrolyte interface. The QDSSC based on the BCNT1 CE and CdS/CdSe photoanode achieves a power conversion efficiency of up to 4.55%, which is 3.10 times that of the pristine CNT CE. Our report confirms that tailorable boron doping is an effective strategy to enhance the activity of CNTs for Sn2− reduction.
One of important factors for improving the power conversion efficiency (PCE) of quantum dot-sensitized solar cells is to enhance the utilization of sunlight. Herein, we modified the wavelength range of incident sunlight from the counter electrode (CE) side to investigate the photoelectric performance of solar cells. The effect of illuminating CuS and Cu 2 S CE with different light ranges (including non-illumination, UV–visible light, NIR light and full-spectrum light) on cell performance was investigated. It has been shown that illuminating from both sides of cell induce substantial increase in PCE, and a 42.8% enhancement in PCE compared with that irradiating from the photoanode side has been achieved with a champion PCE of 5.6% (Voc = 0.6 V, Jsc = 21.7 mA cm −2 ) based on CuS CE. This strategy focuses on the neglected problem of light utilization of the CE, and provides a direction for realizing full-spectrum absorption of liquid-junction solar cells.
Bi2S3 films consisting of two-dimensional interconnected Bi2S3 single-crystalline nanorod networks have been fabricated on a F:SnO2 (FTO) glass substrate through the formation of intermediate BiOI nanosheets from layer-structured BiI3 by chemical vapor deposition and subsequent hydrothermal transformation into Bi2S3 networks. A continuous lattice and structure-directed topotactic transformation mechanism is supposed for the formation of Bi2S3 network film. The prepared Bi2S3/FTO films were employed as counter electrode (CE) for CdSe quantum dot-sensitized solar cells for the first time and showed better photovoltaic performance than that from the convenient Pt CE. The influence of the preparation conditions for Bi2S3/FTO films on the resulting solar cell performance was systematically investigated and optimized with use of J–V curves, scanning electron microscopy (SEM), UV–vis absorption, and electrochemical impedance spectroscopy. To further improve the cell device efficiency, the modification of the Bi2S3 network CE with metal particles was also studied.
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