ACS Energy Letters 最新文献

Cobalt-free, nickel-rich oxides are promising cathode materials with high energy density but suffer from poor reversibility due to unstable surface and anisotropic phase transitions. We report the performance improvement of LiNiO₂ by Mo doping within the bulk and epitaxial growth of Li₄MoO₅ on the surface. Mo-modification exerts multiple effects, including construction of a three-dimensional Li⁺ diffusion channel, reduction in surface reaction activity, and alleviation of structural strain, which collectively enhance Coulombic efficiency and stabilize lattice oxygen up to a charging voltage of 4.8 V. The interdiffusion of Li, Ni, and Mo between the surface Li₄MoO₅ and bulk LiNiO₂ facilitates in situ reconstruction of the surface lattice to form a Mo-rich Li⁺/Ni²⁺ superlattice structure that anchors surface oxygen and promotes liberation of additional Li⁺ from Li₄MoO₅ for charge compensation. This study reveals the dynamic structural changes of Mo-modified LiNiO₂ and proposes strategies to address lithium-loss and structure-instability issues in cycling nickel-rich cathode materials.

Heterostructured quantum dots (QDs) based on narrow-bandgap PbSe and wide-bandgap CdSe have been studied for applications in near-infrared light sources, photodetection, and solar energy conversion. A common structural motif is a QD consisting of a PbSe core enclosed in a CdSe shell. However, the CdSe shell complicates extraction of band-edge charge carriers from the QD. Therefore, conventional PbSe/CdSe QDs are not suitable for application in photoelectric devices. Here we report inverted CdSe/PbSe core/shell QDs that overcome this drawback. In these structures, both the electron and hole exhibit a significant degree of shell localization and can therefore be easily extracted from the QD. To create these structures, we employ a thin, atomically controlled wetting layer that homogenizes the CdSe core surface and thus promotes directionally uniform growth of the PbSe shell. The synthesized CdSe/PbSe QD films exhibit good photocarrier transport, making them suitable for application in photoelectric devices.

Cs₂AgBiBr₆ shows promise for solution-processable optoelectronics, such as photovoltaics, photocatalysis, and X-ray detection. However, various spectroscopic studies report rapid charge carrier mobility loss in the first picosecond after photoexcitation, limiting carrier collection efficiencies. The origin of this rapid mobility loss is still unclear. Here, we directly compare hot excitation with excitation over the indirect fundamental bandgap, using transient absorption and THz spectroscopy on the same Cs₂AgBiBr₆ thin film sample. From transient absorption spectroscopy, we find that hot carriers cool toward the band-edges with a cooling rate of 0.58 ps^–1, which coincides with the observed mobility loss rate from THz spectroscopy. Hence, our study establishes a direct link between the hot carrier cooling and ultrafast mobility loss on the picosecond time scale.

Minimizing optical and electronic losses is essential for achieving high-efficiency solar cells. Inverted (p-i-n) perovskite solar cells (PSCs) have made great strides toward commercialization, yet light transmittance losses in the indium tin oxide (ITO) photoanode within the 400–700 nm visible spectrum remain a challenge. Here, we construct a discrete photonic scaffold at the poly(triaryl amine) (PTAA)/perovskite interface using zirconium dioxide (ZrO₂) nanoparticles, which enhance the visible transmittance of the ITO/PTAA substrate, form a robust perovskite interface, improve photon harvesting, and facilitate the growth of photoactive (100) and (111) perovskite crystal facets. As a result, the ZrO₂-stack devices, with active areas of 0.1 cm² and 1 cm², achieve champion power conversion efficiencies (PCEs) of 25.56% and 24.27%, respectively. The devices retain over 92% of their initial PCEs after 1000 h of 1 sun maximum power point tracking.