The improvement of sunlight utilization is a fundamental approach for the construction of high-efficiency quantum-dot-based solar cells (QDSCs). To boost light harvesting, cosensitized photoanodes are fabricated in this work by a sequential deposition of presynthesized Zn-Cu-In-Se (ZCISe) and CdSe quantum dots (QDs) on mesoporous TiO films via the control of the interactions between QDs and TiO films using 3-mercaptopropionic acid bifunctional linkers. By the synergistic effect of ZCISe-alloyed QDs with a wide light absorption range and CdSe QDs with a high extinction coefficient, the incident photon-to-electron conversion efficiency is significantly improved over single QD-based QDSCs. It is found that the performance of cosensitized photoanodes can be optimized by adjusting the size of CdSe QDs introduced. In combination with titanium mesh supported mesoporous carbon as a counterelectrode and a modified polysulfide solution as an electrolyte, a champion power conversion efficiency up to 12.75% (V = 0.752 V, J = 27.39 mA cm , FF = 0.619) is achieved, which is, as far as it is known, the highest efficiency for liquid-junction QD-based solar cells reported.
Sodium-ion
hybrid capacitors are known for their high power densities
and superior cycle life compared to Na-ion batteries. However, low
energy densities (<100 Wh kg–1) due to the lack
of high-capacity (>150 mAh g–1) anodes capable
of
fast charging are delaying their practical implementation. Herein,
we report a high-performance Na-ion hybrid capacitor based on an interface-engineered
hierarchical TiO2 nanosheet anode consisting of bronze
(∼15%) and anatase (∼85%) crystallites (∼10 nm).
This pseudocapacitive dual-phase anode demonstrated exceptional specific
capacity of 289 mAh g–1 at 0.025 A g–1 and excellent rate capability (110 mAh g–1 at
1.0 A g–1). The Na-ion hybrid capacitor integrating
a dual-phase hierarchical TiO2 nanosheet anode and an activated
carbon cathode exhibited a high energy density of 200 Wh kg–1 (based on the total mass of active materials in both electrodes)
and power density of 6191 W kg–1. These values are
in the energy and power density range of Li-ion batteries (100–300
Wh kg–1) and supercapacitors (5000–15 000
W kg–1), respectively. Furthermore, exceptional
capacity retention of 80% is observed after 5000 charge–discharge
cycles. Outstanding electrochemical performance of the demonstrated
Na-ion hybrid capacitor is credited to the enhanced pseudocapacitive
Na-ion intercalation of the two-dimensional TiO2 anode
resulting from nanointerfaces between bronze and anatase crystallites.
Mechanistic investigations evidenced Na-ion storage through intercalation
pseudocapacitance with minimal structural changes. This approach of
nanointerface-induced pseudocapacitance presents great opportunities
toward developing advanced electrode materials for next-generation
Na-ion hybrid capacitors.
A novel gel electrolyte based on a superabsorbent polyelectrolyte, sodium polyacrylate (PAAS), was developed to construct quasi-solid-state QDSCs, achieving a similar PCE to liquid-junction QDSCs but better stability.
A highly conductive gel electrolyte based on sodium carboxymethylcellulose was developed to construct quasi-solid-state quantum dot sensitized solar cells that exhibit power conversion efficiency over 9% and a significant improvement in stability compared to liquid-junction QDSCs.
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