Improved Carrier Transfer Research Articles

Dramatically Enhancing Multiphoton Harvesting Metal-Organic Frameworks for NIR-II Photocatalysis through Functional Regulation of Octupolar Molecules.

The development of effective multiphoton absorption (MPA) materials for near-infrared (NIR) light-driven photocatalysis holds great significance. In this study, we incorporated two multibranched cyclometallated iridium(III) modules with varying degrees of conjugation onto MPA-inert metal-organic frameworks (MOFs) to active MPA performance. Subsequently, the MOFs were further modified with Co(II) and hyaluronic acid (HA) to fabricate MINCH and MISCH, respectively. By introducing octupolar molecules and expanding the conjugation, MISCH exhibited a larger MPA cross section for efficient NIR light absorption and improved carrier transfer, leading to outstanding NIR light-driven multiphoton photocatalytic hydrogen production. Moreover, the HA modification enabled MISCH to achieve specific multiphoton photocatalytic hydrogen therapy for cancer cells. This study provides valuable insights into constructing highly active MPA materials for NIR light-driven photocatalysis, presenting a potential platform for hydrogen therapy in tumor treatment.

Au Nanocluster Assisted Microstructural Reconstruction for Buried Interface Healing for Enhanced Perovskite Solar Cell Performance.

The heterogeneity of perovskite film crystallization along the vertical direction leads to voids and traps at the buried interfaces, hampering both efficiency and stability of perovskite solar cells. Here, bovine serum albumin-functionalized Au nanoclusters (ABSA), combined with heavy gravity, high surface charge density, and strong interactions with the electron transport layer, are designed to reconstruct the buried interfaces for not only high-quality crystallization, but also improved carrier transfer. The ABSA macromolecules with amine function groups and larger surface charge density interact with the perovskite to improve the crystallinity, and gradually migrate towards the buried interface, healing the defective voids, hence suppressing surface recombination velocity from 3075 to 452 cm s-1 . The healed buried interface and the higher surface potential of ABSA-modified TiO2 lead to improved carrier extraction at the interface. The resulting solar cell attains a power conversion efficiency of 25.0% with negligible hysteresis and remarkable stability, maintaining 92.9% of their initial efficiency after 3200 h of exposure to the ambient atmosphere, they also exhibit better continuous irradiation stability compared to control devices. These findings provide a new metal-protein complex to eliminate the deleterious voids and defects at the buried interface for improved photovoltaic performance and stability.

Porphyrin-based donor with asymmetric ending groups enables 16.31% efficiency for ternary all-small-molecule organic solar cells

A great attention has been aroused by all-small-molecule organic solar cells (ASM OSCs), thanks to characteristics of small molecules such as well-defined chemical structure and excellent reproducibility between batches. However, it is such a challenge to balance the aggregation behaviors of small molecules, which causes hardship for morphology optimizing of active layers, limiting further efficiency developing for ASM OSCs. Recently, the asymmetric ending group strategy has been employed in non-fullerene acceptors (NFAs) and gained great success. Herein, enlightened by the asymmetric NFAs molecule design, two asymmetric and symmetric small molecule donors, Por-DPP-TR and PTR, were synthesized. Compared to PTR, Por-DPP-TR displays an enlarged dipole moment and enhanced crystallization property. In binary OSCs, contributing to the improved film morphology, Por-DPP-TR:6TIC-based device performed an efficiency of 13.28%. Moreover, ternary ASM OSCs were constructed by employing an isogenous porphyrin-based donor, ZnP-TSEH, and an efficiency of 16.31% was obtained thanks to the further improved carrier transfer properties as well as the well-tuned morphology of obvious bi-continuous network. As far as we know, 16.31% ranks as one of the highest PCEs for ASM OSCs.

TiO2 passivation layers with laser derived p-n heterojunctions enable boosted photoelectrochemical performance of α-Fe2O3 photoanodes

Addressing the carrier loss at the semiconductor-liquid junction of metal oxides is of significance for developing high-performance photoelectrodes for viable solar hydrogen generation, while one of the critical challenges remains in pursuing the top passivation layer with pronounced carrier extraction capability. In the present work, we propose and experimentally verify that artificial engineering of the passivation layer via laser embedding of p-n heterointerfaces leads to significantly improved carrier transfer. By virtue of the advantage of generating nanocrystals in any desired solvents via the technology of laser synthesis and processing of colloids (LSPC), p-type CdTe nanocrystals are successfully embedded in a thin layer of TiO2, which is adopted as an efficient passivation layer to address the excessive surface defects and the slow carrier transfer at α-Fe2O3 photoanodes. The embedded p-n heterointerfaces not only provide an effective built-in electric field that accelerates carrier transport in TiO2 via boosting polaron hopping but also activate hole transfer by shifting up the valence band in TiO2. Such vivid embedding is demonstrated to generate a 12-fold increase for the lifetime of photogenerated electrons, and a 3.9-fold increase for the ηinj at 1.23 VRHE, leading to a 4.4-fold increase in the photocurrent density at 1.23 VRHE. We thus believe the present work provides a universal alternative for regulating the chemical/physical features of semiconductor-liquid junctions at metal oxides.

Improved Photoelectrochemical Hydrogen Gas Generation on Sb2S3 Films Modified with an Earth-Abundant MoSx Co-Catalyst

Antimony(III) sulfide (Sb2S3) has recently emerged as an outstanding potential photoelectrode due to its superlative optoelectronic properties for light-driven water splitting application. However, the occurrence of the recombination process in this material is regarded as one of the main limiting factors to date. Herein, we greatly suppressed the occurrence of recombination and improved carrier transfer via photoelectrodepositing an earth-abundant MoSx co-catalyst over Sb2S3 films. The Sb2S3/MoSx films displayed a remarkable 2-fold increase of their photoresponse for H2 generation and also resulted in shifting the onset potential approximately 100 mV to less negative values. Based on an in-depth analysis of the transients’ photocurrent density, the enhanced photoresponse was assigned to a smaller probability of the electron–hole recombination process, as noted from the substantial reduction of the accumulated negative charge density values at the surface of the Sb2S3 films. The minimization of carriers recombination was also verified from the decrease of the charge transfer resistance values by approximately 2-fold for the Sb2S2/MoSx films. Additionally, Sb2S3/MoSx featured an increase of the space charge thickness, which suggests an improvement of carrier separation or a minimized recombination process due to the enlarged gradient of the (quasi-)Fermi level in the space charge region of the Sb2S3 films.

Improved carrier transfer in vertically coupled surface and buried InAs Stranski-Krastanov quantum dot system via ex-situ surface state passivation

In this work, the authors have investigated the optical and morphological characteristics of uncapped InAs quantum dots (QDs) and their sensitivity to the surface passivation. The temperature dependent carrier transfer mechanism between self-assembled vertically coupled InAs surface quantum dot (SQD) and underneath buried quantum dot (BQD), separated by a thin spacer layer is investigated. Oxide layer etching followed by surface passivation has been carried out to deplete the surface states and improve the structural/optical behaviour of uncapped InAs SQDs. The passivation time has been varied from 0.5 to 2.5 h and its effect on the optical and morphological properties is investigated. The larger SQDs are resized to smaller ones and show lower size dispersion after the etching process. Additionally, an increased energy level overlapping between SQD and BQD is obtained after the etching process. This partial overlap of energy levels further corroborates the enhanced electronic communication achieved between the surface and underneath buried dots. The sample, with 1 h of surface passivation, unveils as the best among all in terms of stronger luminescence from the SQD. Through this study, the SQDs are projected as the primary receptor, whereas the BQDs behave like carrier reservoirs. Hence, the BQDs would provide the carriers to enhance the sensitivity of the SQDs, which would impact the performance of QD based sensors.

SPR-Effect Enhanced Semimetallic Bi0/p-BiOI/n-CdS Photocatalyst with Spatially Isolated Active Sites and Improved Carrier Transfer Kinetics for H2 Evolution

Bi0/p-BiOI/n-CdS was firstly designed to applied to hydrogen evolution by water splitting. UV-vis DRS tests show that Bi0 has a SPR absorption peak at 428 nm. Theoretical calculations show that ele...

High performance planar perovskite solar cells based on CH3NH3PbI3-x(SCN)x perovskite film and SnO2 electron transport layer prepared in ambient air with 70% humility

In this work, the efficient and stable planar perovskite solar cells (PSCs) based on CH3NH3PbI3-x(SCN)x perovskite layer and low-temperature processed SnO2 electron transport layer (ETL) have been fabricated in ambient air with 70% humility. The maximum processing temperature of the PSCs is only 150 °C. The effect of SnO2 solution concentrations on photoelectronic characteristics of the PSCs has been symmetrically investigated. At the optimized SnO2 concentration, the PSCs based on SnO2 ETL (SnO2-PSCs) achieve the champion power conversion efficiency (PCE) of 16.23% and average PCE of 15.82%, being much higher than that of the reference PSCs based on TiO2 ETL. The higher PCE of SnO2-PSCs can be attributed to the improved carrier transfer and collection, and the suppressed charge recombination. Importantly, the SnO2-PSCs without encapsulation demonstrate an excellent long-term stability. After being stored in ambient air with 70% humidity for 30 days, the PCE of the unsealed SnO2-PSCs decay only 15%. This work presents a simple low-temperature solution method to fabricate efficient and stable PSCs in ambient air with high humidity, which is beneficial for future application of PSCs.

Improved Carrier Transfer in Red Organic Light Emitting DiodesDoped with Rubrene

A red organic light emitting diode doped with rubrene is constructed withthe configuration ofITO/NPB/Alq3:rubrene:DCM/Alq3/LiF/Al. In the device,N,N'-bis-(1-naphthl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB) isused as the hole-transporting layer, tris(8-quinolinolato) aluminium(Alq3) as the electron-transporting layer and Alq3 doped with5,6,11,12-tetraphenylnaphthacene (rubrene) and4-dicyanomethylene-2-methyl-6-(p-dimethyla-minostyryl)-4H-pyran (DCM)as the emitting layer. When the doping concentration of rubrene is 6% andthat of DCM is 4%, red purity of the device is improved effectively. Theexperimental phenomena are explained as the result of the improved carriertransfer from rubrene to DCM.