Search

The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non-emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance. [ABSTRACT FROM AUTHOR]

For Z907-based dye-sensitized solar cells, we constructed photoanodes, layer by layer, containing titania nanostructures of varied types - spherical nanoparticles (NPs), one-dimensional nanorods (NRs), and octahedron-like nanocrystals of varied size (HD1-HD3), in either a bi-layer (BL) or a multi-layer (ML) film configuration. To understand the kinetics of electron transport in these devices, we measured charge extraction, intensity-modulated photocurrent spectra and photovoltage spectra of devices made of either these nanomaterials or hybrid HD-NP composites (HDP). The HD devices featured an excellent characteristic of electron transport and upward-shifted potentials to produce V[sub OC] greater than those of the NP and NR devices, but the latter featured a larger dye loading to give J[sub SC] greater than that for the former; the devices fabricated with hybrid HDP films showed enhanced J[sub SC] and balanced V[sub OC] to perform better than their individual counterparts. We constructed the ML devices based on the NP-BL system with additional HDP layers inserted between the two components, NP and SL, to enhance JSC so as to attain the best performance, with efficiency of power conversion (PCE) = 10.1%, at a film thickness (L)of26 μm. Because of the robust structural feature of the HD films, the devices fabricated with a simple BL film configuration, HD1/SL = 6/3, exhibited the best performance, PCE = 10.2% at L = 29 μm, which is a promising advance for Z907-based solar cells with a superior and enduring stability of performance for commercialization. [ABSTRACT FROM AUTHOR]

In response to the urgent need for advanced climate change mitigation tools, this study introduces an innovative CO 2 gas sensor based on p-p-type heterostructures designed for effective operation at room temperature. This sensor represents a significant step forward, utilizing the synergistic effects of p-p heterojunctions to enhance the effective interfacial area, thereby improving sensitivity. The incorporation of CuO nanoparticles and rGO sheets also optimizes gas transport channels, enhancing the sensor's performance. Our CuO/rGO heterostructures, with 5 wt % rGO, have shown a notable maximum response of 39.6-500 ppm of CO 2 at 25 °C, and a low detection limit of 2 ppm, indicating their potential as high-performance, room-temperature CO 2 sensors. The prepared sensor demonstrates long-term stability, maintaining 98% of its initial performance over a 30-day period when tested at 1-day intervals. Additionally, the sensor remains stable under conditions of over 40% relative humidity. Furthermore, a first-principles study provides insights into the interaction mechanisms with CO 2 molecules, enhancing our understanding of the sensor's operation. This research contributes to the development of CO 2 monitoring solutions, offering a practical and cost-effective approach to environmental monitoring in the context of global climate change efforts.

The excitonic relaxation dynamics of perovskite adsorbed on mesoporous thin films of Al2O3 and NiO upon excitation at 450 nm were investigated with femtosecond optical gating of photoluminescence (PL) via up-conversion. The temporal profiles of emission observed in spectral region 670-810 nm were described satisfactorily with a composite consecutive kinetic model and three transient components representing one hot and two cold excitonic relaxations. All observed relaxation dynamics depend on the emission wavelength, showing a systematic time-amplitude correlation for all three components. When the NiO film was employed, we observed an extent of relaxation proceeding through the non-emissive surface state larger than through the direct electronic relaxation channel, which quenches the PL intensity more effectively than on the Al2O3 film. We conclude that perovskite is an effective hole carrier in a p-type electrode for NiO-based perovskite solar cells showing great performance., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)