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NIR polymers and phototransistors
摘要： A novel bisthiophene-fused diketopyrrolopyrrole unit (4,11-bis(2-octyldodecyl)-7H,14H-thieno[30,20:7,8]indolizino[2,1-a]thieno[3,2-g]indolizine-7,14-dione, BTI) has been designed as an electron acceptor and used to copolymerize with thiophene and bithiophene as electron donors to construct two D–A conjugated polymers, P1 and P2 via Stille coupling, respectively. The two polymers showed excellent thermal stability, broad light absorption and a narrow energy band gap. P1 and P2 were used to fabricate organic field-effect transistors (OFETs) to evaluate their charge transport characteristics. P2 showed much better hole transport performance with a mobility of 0.1 cm2 V?1 s?1. Near-infrared (NIR) phototransistors were also fabricated by using the two polymers blended with PC71BM as the active layer. With illumination of 35 mW cm?2 at a wavelength of 850 nm, the photocurrent/dark-current ratio (P) and photoresponsivity (R) of the phototransistor based on P1/PC71BM were 3.6 × 104 and 270 A W?1, respectively. For P2/PC71BM, P was 2.5 × 104 and R reached 2420 A W?1.
关键词： phototransistors,photoresponsivity,organic field-effect transistors,diketopyrrolopyrrole,NIR polymers,charge transport
更新于2025-09-19 17:15:36
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Charge transport properties in organic D-A mixed-stack complexes based on corannulene and sumanene derivatives-a theoretical study
摘要： A series of corannulene and sumanene derivatives (C-series and S-series) has been designed as organic D-A mixed-stack cocrystal complexes. The intermolecular interaction energies, frontier molecular orbitals, super-exchange electronic coupling and visualization of the orbital overlap integrals have been investigated by means of DFT method. The molecular stacking configuration in the crystal was predicted by calculating the interaction potential energy. The super-exchange mechanism has been applied to study the charge transport properties. It can be predicted that the C-series D/A complexes have potential superiority of electron transport, especially for C/C-5F. Nevertheless, the S-series D/A complexes have intrinsic electron transport weakness. Our findings can provide a better understanding of the structure-property relationship of corannulenes and sumanenes as novel D-A mixed-stack cocrystal charge-transfer systems.
关键词： charge transport property,corannulene,DFT,sumanene,D-A mixed-stack cocrystal
更新于2025-09-19 17:15:36
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Naphthalene Diimide-Based Terpolymers with Controlled Crystalline Properties for Producing High Electron Mobility and Optimal Blend Morphology in All-Polymer Solar Cells
摘要： We report a series of new n-type random copolymers (P(NDI2OD-Se-Th x) where x = 0, 0.5, 0.7, 0.8, 0.9, 1.0) consisting of naphthalene diimide (NDI), selenophene-2,2’-thiophene (Se-Th), and seleno[3,2-b]thiophene (SeTh) to demonstrate their use in producing efficient all-polymer solar cells (all-PSCs) and organic field-effect transistors (OFETs). To investigate the effect of polymer crystallinity on the performance of all-PSCs and OFETs, we tuned the composition of the Se-Th and SeTh moieties in the P(NDI2OD-Se-Th x) polymers, resulting in enhanced crystalline properties with higher Se-Th ratio. Thus, the OFET electron mobility was increased with higher Se-Th ratio, exhibiting the highest value of 1.38×10?1 cm2 V?1 s?1 with P(NDI2OD-Se-Th 1.0). However, the performance of all-PSCs based on PBDB-T:P(NDI2OD-Se-Th x) showed a non-linear trend relative to the Se-Th ratio and the performance was optimized with P(NDI2OD-Se-Th 0.8) exhibiting the highest power coversion efficiency of 8.30%. This is attributed to the stronger crystallization-driven phase separation in all-polymer blends for higher Se-Th ratio. At the optimal crystallinity of P(NDI2OD-Se-Th 0.8) in all-PSCs, the degree of phase separation, domain purity and the electron mobility were optimized, resulting in enhanced charge generation and transport. Our works describe structure-property-performance relationships to design effective n-type polymers in terms of crystalline and electrical properties suitable for both efficient OFETs and all-PSCs.
关键词： organic field-effect transistors,seleno[3,2-b]thiophene,polymer crystallinity,n-type random copolymers,selenophene-2,2’-thiophene,charge generation,all-polymer solar cells,charge transport,naphthalene diimide
更新于2025-09-19 17:13:59
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The Effect of Titanium (IV) Chloride Surface Treatment to Enhance Charge Transport and Performance of Dye-Sensitized Solar Cell
摘要： In this study, the photovoltaic and electrochemical characteristics of the dye-sensitised solar cell (DSSC) after Titanium (IV) Chloride (TiCl4) treatment on a TiO2 photoelectrode were investigated. Photoelectrodes of untreated, pre-TiCl4 and post-TiCl4 treatment were prepared to form a complete DSSC. The photoelectrode was sensitised in 40mM of TiCl4 solution at 80 °C for 30 minutes, and then it is sintered at 500 °C. The morphology of photoelectrodes has been studied using FESEM, and it was found that, after TiCl4 treatment, the particle necking and particle size of TiO2 nanoparticles were increased significantly. Therefore, it improved the electron transfer path on the TiO2 layer. Subsequently, the the light absorption intensity after post-TiCl4 treatments was increased due to strong adhesion and homogeneity of the TiO2 layer on the FTO substrate, which results in higher current density and photon-conversion efficiency by 18.95 mAcm-2 and 8.03% when compared to an untreated electrode at 12.1 mAcm-2 and 4.08% (increment of 56.7% and 96.9%), respectively. Electrochemical impedance spectroscopy used to study the internal electrochemical characteristics of DSSC after the treatment. Thus, it proves that the treatment suppresses the charge recombination between TiO2 and the electrolyte interface by increasing charge transfer resistance after post-TiCl4 treatment by 24.06Ω from 16.11Ω for untreated photoelectrodes (increment of 49.39%). The electron lifetime also improved from 0.4 to 1.59 ms, which results in the enhancement of charge collection efficiency after post-treatment by 31.09% compared to the untreated electrode. Improvement of charge collection efficiency indicated that the TiCl4 treatment had played an important role in charge separation and charge collection on the TiO2 and electrolyte interface of DSSC.
关键词： charge transport,DSSC surface treatment,TiCl4,charge collection efficiency (CCE)
更新于2025-09-19 17:13:59
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Efficient Charge Transfer and Carrier Extraction in All-Polymer Solar Cells Using an Acceptor Filler
摘要： All-polymer solar cells (all-PSCs) exhibit considerably improved mechanical and thermal stability than their polymer-fullerene counterparts. Despite their advantages, the power conversion efficiencies of all-PSCs are still lower than those of polymer-fullerene PSCs. In this study, we demonstrate that introducing a small amount of fullerene or nonfullerene acceptors as filler into the photoactive layer of PBDBT:N2200 all-PSCs can enhance charge transport properties, thereby the device performance. An appreciable enhancement (~21%) in the power-conversion-efficiencies (PCEs) of all-PSCs, from 6.13% to 7.42%, is obtained when fullerene with the amount of 25 wt% PBDBT is added. The performance improvement is primary from the enhanced short circuit current density (Jsc), which can be attributed to the enhanced exciton dissociation, reduced charge recombination, and balanced charge transport in the prescence of the fullerene filler. Similar behavior is also observed when fullerene is replaced by ITIC molecules. Importantly, the fullerene filler shows a negiligible effect on the device storage and light-soaking stability. Therefore, all-PSCs incorporating a proper selected acceptor filler is an efficient way to improve device performance without sacrificing stability. We believe that our study can pave a useful approach for developing stable and high performance PSCs.
关键词： filler,all-polymer solar cell,charge transport,ternary,charge extraction
更新于2025-09-19 17:13:59
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High charge carrier mobility in solution processed one-dimensional lead halide perovskite single crystals and their application as photodetectors
摘要： Organic inorganic hybrid metal halide perovskites have emerged as promising candidates for photovoltaics and light-emitting diodes. Recently, interest has been growing in the properties of low-dimensional metal halide perovskites, and one-dimensional versions with strong quantum confinement have demonstrated highly efficient broadband luminescence. Nevertheless, the charge transport mechanism in these low dimensional perovskites remains unclear. In this work, we characterised the charge mobility in one-dimensional perovskite single crystals using a space charge limited current method. Temperature dependent charge mobility measurements indicated that localized polarons at high temperature are replaced by delocalized polarons at low temperature with extended states in the polaronic band. A minimum mobility of 4.51 cm2/Vs was measured at room temperature. UV photodetectors based on these crystals show an ultrahigh photoresponsivity of 132.3 A W-1. These findings show the promise of high mobility low dimensional perovskite materials for optoelectronic applications.
关键词： space charge limited current,low-dimensional,charge transport,photodetectors,organic-inorganic hybrid metal halide perovskites
更新于2025-09-19 17:13:59
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Understanding resonant charge transport through weakly coupled single-molecule junctions
摘要： Off-resonant charge transport through molecular junctions has been extensively studied since the advent of single-molecule electronics and is now well understood within the framework of the non-interacting Landauer approach. Conversely, gaining a qualitative and quantitative understanding of the resonant transport regime has proven more elusive. Here, we study resonant charge transport through graphene-based zinc-porphyrin junctions. We experimentally demonstrate an inadequacy of non-interacting Landauer theory as well as the conventional single-mode Franck–Condon model. Instead, we model overall charge transport as a sequence of non-adiabatic electron transfers, with rates depending on both outer and inner-sphere vibrational interactions. We show that the transport properties of our molecular junctions are determined by a combination of electron–electron and electron-vibrational coupling, and are sensitive to interactions with the wider local environment. Furthermore, we assess the importance of nuclear tunnelling and examine the suitability of semi-classical Marcus theory as a description of charge transport in molecular devices.
关键词： Marcus theory,single-molecule junctions,electron-vibrational coupling,electron transfers,resonant charge transport,Landauer theory,Franck–Condon model,electron–electron interactions
更新于2025-09-19 17:13:59
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Numerical simulation of charge transport layer free perovskite solar cell using metal work function shifted contacts
摘要： Perovskite solar cells (PSCs) are one of the fastest emerging photovoltaic (PV) technology at the research level. To achieve higher conversion efficiencies from PSCs, a perovskite absorber layer is stacked between two charge transport layers (CTLs) such as electron and hole transport layers. However, fabrication of defect-free multi-layered PSC is a challenging task, and the presence of CTL and their corresponding interfaces with perovskite enhances the recombination, hysteresis and led to poor stability. Here, in this work, CTL free (i.e., electron and hole transport layer free) PSC is simulated using metal work function shifted contacts. The device presented in this work is free from transport layers and the collection process is with the help of an electric field across the perovskite layer. The electric field is created by using two metals of different work function, i.e., 4.35eV and 5.25eV (can be realized using self-assembled monolayers technique) used as cathode and anode respectively. Simulated CTL free PSC exhibits JSC=17.8 mA.cm-2, VOC=712 mV, FF=68.5% and PCE=8.7% with 250 nm thick perovskite absorber layer having bulk defect density of 2.5x1013 cm-3. Further, a comprehensive study is done in terms of front electrode work function (FEW), front electrode transparency, perovskite thickness and bulk defect density to understand the impact of these parameters on the performance of the device. To understand the behavior of the device, the energy band diagram profile is examined. Reported results show that higher metal work function difference between front and back electrode, higher transparency, and thick perovskite layer with low defect density results in better PV effect in CTL free PSC. Optimized CTL free PSC device delivers JSC=19.9 mA.cm-2, VOC=726 mV, FF=66.8% and PCE=9.7%. The design simulated in this work opens up a new window for next-generation interface defect and hysteresis-free PSC.
关键词： simulation,absorption,SCAPS-1D.,charge transport layer,metal work function,Perovskite solar cell,transparency
更新于2025-09-19 17:13:59
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Synergistic effect of additives on 2D perovskite film towards efficient and stable solar cell
摘要： Recently，two-dimensional (2D) organic-inorganic hybrid perovskites have attracted tremendous attention due to their excellent environment stability. However, the inhibition of out-of-plane charge transport limits the performance of 2D based perovskite solar cells (PVSCs). To overcome this issue, we prepare the vertical-orientated 2D perovskite film via introducing dimethyl sulfoxide (DMSO) and thio-semicarbazide (TSC) as additives into the precursor solution. High-quality 2D (BA)2(MA)3Pb4I13 (BA = n-butylammonium, MA = methylammonium) films with uniform morphology, increased grain size, intensified crystallinity and vertical orientation are therefore fabricated by a synergistic effect of additives. As a result, the trap-state density in 2D (BA)2(MA)3Pb4I13 films is reduced and the charge transport is remarkably improved. The power conversion efficiency (PCE) of the PVSCs is boosted from the 1.05% to 14.15%. An unsealed device retains 90.3% of its initial PCE after 720 h storage in air atmosphere with relative humidity of 25 ± 5% at 25 °C. The results show the synergistic effect of TSC and DMSO on perovskite films is an effective approach toward efficient and stable 2D PVSC.
关键词： stability,charge transport,orientation,synergistic effect,crystallization process,2D perovskite
更新于2025-09-19 17:13:59
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Niobium doped TiO2 nanorod arrays as efficient electron transport materials in photovoltaic
摘要： One-dimensional (1-D) rutile TiO2 nanorod arrays (NRAs) synthesized by a hydrothermal method suffer from low electrical conductivity and large amounts of surface defects, hindering their further applications. Nb doping is thus introduced to modify their electronic properties. Results indicate that light Nb doping reduces rod nanosizes, increases electron concentrations, decreases surface defective oxides and lowers conduction band of the TiO2 NRAs, while heavy doping induces transformations of morphologies and crystalline orientations as well as occurrences of compositional deviations and low oxidative states of Ti3t. After 0.1 mol% and 1 mol% Nb incorporations, device efficiencies are substantially improved by ~16% and ~33% for the model perovskite and dye-sensitized solar cells, respectively, which are ascribed to reduced recombination at the perovskite/TiO2 interfaces (e.g. charge lifetime increasing from 62 μs to 107 μs) and improved electron transport through the photoanode of TiO2 NRAs (e.g. electron diffusion length increasing from ~14 μm to ~50 μm). Our study verifies that Nb doped 1-D TiO2 NRAs are versatile electron transporting materials in different kinds of emerging solar cells, and are also potential for other fields including photocatalysis, sensors and batteries etc.
关键词： TiO2 nanorod array,Dye-sensitized solar cell,Niobium doping,Charge transport,Perovskite solar cell,Recombination
更新于2025-09-19 17:13:59