High Voc Research Articles

12.3% Efficient Low Voc Loss Pure Sulfide Kesterite Solar Cells from DMSO Solution via Cadmium Alloying

AbstractCd alloying has been theoretically proved to be an effective strategy to suppress Cu‐Zn antisite defects and related defect cluster for improving device performance of pure sulfide kesterite Cu2ZnSnS4 (CZTS) thin film solar cells. However, the potential of Cd alloying has not been fully realized by solely doping without further post heat‐treatment. Here, Cd alloying CZTS (Cu2(Zn,Cd)SnS4, CZCTS) is reported through dimethyl sulfoxide (DMSO) solution and how alloying concentration affects reaction path, grain growth, and electronic properties of the CZCTS absorbers is investigated. This study found that Cd can be incorporated into CZTS through direct phase transformation grain growth, which sufficiently suppresses band tailing. High quality CZCTS absorber films and efficient solar cells are fabricated within a wide range of alloy concentration. A champion CZCTS device with a power conversion efficiency of 12.3% is achieved at 35% Cd concentration without any post heat treatment, improved by over 70% compared to 7.0% of CZTS. This device exhibits a high VOC gain to the Shockley–Queisser (Voc/VocSQ = 59.7%), the lowest VOC deficit achieved in pure sulfide kesterite solar cells. The results demonstrate the importance of the Cd alloying strategy for mitigating band tailing and achieving high efficiency pure sulfide kesterite solar cells.

A combination of fluorine-induced effect and co-sensitization for highly efficient and stable dye-sensitized solar cells.

Developing dyes with high open-circuit photovoltage (Voc) is a vital strategy to improve the power conversion efficiency (PCE) of co-sensitized solar cells (co-DSSCs). Herein, three organic fluorine-containing dyes [YY-ThP(3F), YY-ThP(2F), and YY-ThP(26F)] are designed and synthesized for investigating the fluorine-induced effect on photophysical and photovoltaic performances. Consequently, this effect can significantly broaden the UV-vis absorption spectra of dyes but fail to improve the light-harvesting capability of DSSCs. Strikingly, YY-ThP(3F), featuring 3-position fluorine substitution to cyanoacrylic acid, yields a relatively high Voc compared to the corresponding fluorine-free dye (YY-ThP). Furthermore, the co-sensitization of YY-ThP+YY-ThP(3F) achieves a remarkably high PCE and long-term stability. This work implies that the combination of judicious molecular engineering and co-sensitization is a promising strategy for highly efficient and stable DSSCs.

High‐Voltage Quasi‐Solid‐State Dye‐Sensitized Solar Cells Based on Copper Redox Shuttles

Electrolyte with copper redox shuttles has endowed dye‐sensitized solar cells (DSSCs) with a high open‐circuit voltage (V oc) over 1.0 V and promising efficiencies under the sun and indoor light, but further combining these copper redox shuttles with quasi‐solid‐state gel polymer electrolytes (GPEs) is still a great challenge. The crystallization of polymers inside GPEs is one of the important factors to limit the mass transport of large‐sized copper redox shuttles and dramatically reduce the efficiency of quasi‐solid‐state DSSCs. Herein, the copper‐based GPEs are fabricated via in situ UV‐induced copolymerization of acrylic monomers. This chemical cross‐linking strategy can significantly reduce the crystallinity of polymers inside the GPEs and thus improve the apparent diffusion coefficient two times compared with the generally used poly(ethylene oxide) GPEs. Finally, optimized GPEs, copolymerized by diacrylic and triacrylic monomers, successfully generate the quasi‐solid‐state DSSCs with an efficiency of 10.1% and a high V oc of 1.03 V. These photovoltaic parameters are comparable to those of DSSCs with liquid copper‐based electrolytes, demonstrating that the chemical cross‐linking is an effective strategy to fabricate high‐performance copper‐based GPEs. This strategy will facilitate the future efficiency and stability improvement of DSSCs for the commercial optoelectronic applications.

Triple-electrode integrated self-supporting triboelectric nanogenerators with high output and durability based on dynamic supercritical carbon dioxide foaming

Durable and sustainable energy harvesting in harsh environments using triboelectric nanogenerators (TENGs) is a grand challenge. Herein, highly compacted and integrated TENGs are developed using dynamic supercritical carbon dioxide (scCO2) foaming technique. The self-assembled internal-electrode TENG (SAI-TENG) which is consisted of a polydimethylsiloxane (PDMS) coated internal metal electrode covered by a corrugated wrinkled foam (CWF) is readily obtained by the foaming process. The CWF can support itself and maintains air gaps to facilitate contact electrification and the biomimetic wrinkles that are induced by the scCO2 flow field, greatly enhance the triboelectric output performance. By sandwiching the SAI-TENG using two internal-electrode PDMS films, a triple-electrode integrated self-supporting TENG (TIS-TENG), which has eight-friction layers in a single device, is developed. The TIS-TENG realized maximum utilization of the wrinkled CWF surface, which is equivalent to three parallel connected TENGs. Moreover, the output was further boosted by adding tea powders and patterning micro domes on the PDMS films, which resulted in a high Voc of 106.3 V and a power density of 32.5 mW/m2. Attributing to the embedded electrode and high elasticity of CWF, the TIS-TENG has remarkable stability and tolerance to harsh conditions and can be used as self-powered sensors for monitoring vehicle parking and working conditions of workers. This work provides new insights into the green fabrication and development of highly integrated self-supporting TENGs with high performance and durability.

SnF2‐Doped Cs2SnI6 Ordered Vacancy Double Perovskite for Photovoltaic Applications

Air‐stable p‐type SnF2:Cs2SnI6 with a bandgap of 1.6 eV has been demonstrated as a promising material for Pb‐free halide perovskite solar cells. Crystalline Cs2SnI6 phase is obtained with CsI, SnI2, and SnF2 salts in gamma‐butyrolactone solvent, but not with dimethyl sulfoxide and N,N‐dimethylformamide solvents. Cs2SnI6 is found to be stable for at least 1000 h at 100 °C when dark annealed in nitrogen atmosphere. In this study, Cs2SnI6 has been used in a superstrate n–i–p planar device structure enabled by a spin‐coated absorber thickness of ≈2 μm on a chemical bath deposited Zn(O,S) electron transport layer. The best device power conversion efficiency reported here is 5.18% with VOC of 0.81 V, 9.28 mA cm−2 JSC, and 68% fill factor. The dark saturation current and diode ideality factor are estimated as 1.5 × 10−3 mA cm−2 and 2.18, respectively. The devices exhibit a high VOC deficit and low short‐circuit current density due to high bulk and interface recombination. Device efficiency can be expected to increase with improvement in material and interface quality, charge transport, and device engineering.

Illumination Enhanced Crystallization and Defect Passivation for High Performance CsPbI3 Perovskite Solar Cells by Sacrificing Dye

AbstractAll‐inorganic perovskite solar cells (PSCs) have been the research focus due to their high thermal stability and proper band gap for tandem solar cells. However, their power conversion efficiency (PCE) is still lower than that of organic‐inorganic hybrid PSCs. Herein, a sacrificing dye (Rhodamine B isothiocyanate, RBITC) is developed to regulate the growth of perovskite film by in situ release of ethylammonium cations, isothiocyanate anions and benzoic acid molecules upon annealing and illumination. The ethylammonium cations can efficiently passivate surface defects. The isothiocyanate anions incorporate with uncoordinated Pb to regulate the crystallization process. The benzoic acid molecules facilitate the nucleation of the perovskite crystals. Especially, the illumination can accelerate the release of these beneficial ions/molecules to improve the quality of perovskite films further. After optimization with RBITC, a high open circuit voltage (VOC) of 1.24 V and a champion PCE of 20.95% are obtained, which are among the highest Voc and PCE values of CsPbI3 PSCs. Accordingly, the operational stability of the PSC devices is significantly improved. The results provide an efficient chemical strategy to regulate the formation of perovskite films in whole crystallization process for high performance all‐inorganic PSCs.

TD-DFT and DFT Investigation on Electrons Transporting Efficiency of 2-Cyano-2-Pyran-4-Ylidene-Acetic Acid and 2-Cyanoprop-2-Enoic Acid as Acceptors for Thiophene-Based π-Linkers Dye-Sensitized Solar Cells

Great attention is being shifted to Dye-sensitized solar cells because of their structural and electronic tunability, high performance, and low cost compared to conservative photovoltaic devices. In this work, B3LYP/6-31G** level of theory was used to study the molecular architecture of the donor-π-acceptor (D-π-A) type. This architecture contains a series of dyes with the 2-cyano-2-pyran-4-ylidene-acetic acid (PLTP-dye) and 2-cyanoprop-2-enoic acid (CLTP-dye) units as acceptors; donor groups and thiophene-based π-linkers. The molecular and electronic properties, light harvesting efficiency, open circuit voltage (VOC), injection force (ΔGinject), regeneration force (ΔGregen) and excitation state lifetime (𝜏𝑒𝑠𝑙 ) were calculated. CLTP-dyes showed lower band gap, chemical hardness (η), chemical potential (μ), higher electrophilicity (ω) and electron denoting power (ω-) than the corresponding PLTP-dyes. The ω- demonstrated that PLTP-1, PLTP-2 and PLTP-3, CLTP-1, CLTP-2 and CLTP-3 should readily push electrons to the π-linker, which can lead to high intra-molecular charge transfer and photocurrent for the dyes. The Voc and ΔGinject parameters favoured the CLTP-dyes over corresponding PLTP-dyes, and also dyes with the N,N-diphenylaniline donor have higher Voc, ΔGinject values and longer wavelengths (λmax) than the dyes with carbazole unit (N,N-diphenylaniline dyes > Carbazole dyes) in accordance with the calculated ω-, although all the dyes have good regeneration and injection abilities

Strategies for realizing high-efficiency silicon heterojunction solar cells

Silicon heterojunction (SHJ) solar cells have achieved a record efficiency of 26.81% in a front/back-contacted (FBC) configuration. Moreover, thanks to their advantageous high VOC and good infrared response, SHJ solar cells can be further combined with wide bandgap perovskite cells forming tandem devices to enable efficiencies well above 33%. In this study, we present strategies to realize high-efficiency SHJ solar cells through combined theoretical and experimental studies, starting from the optimization of Si-based thin-film layers to the implementation of electrodes with reduced indium and silver usage. Advanced opto-electrical simulations, which enable comprehensive theoretical understandings of the main physical mechanisms governing carriers’ collection and light management, provide clear pathways for device designs and experimental optimizations. We present the fabricated FBC-SHJ solar cells in both monofacial and bifacial configurations with the best efficiencies of 24.18% and 23.25%, respectively. We point out that to achieve optimum device performance, the compositional materials should be holistically optimized and evaluated as part of the contact stacks with adjacent layers. As an outlook beyond the classical FBC-SHJ solar cell architecture, we propose various novel SHJ-based solar cell architectures. Their potential performance was assessed and compared via rigorous opto-electrical simulations and a maximal efficiency of 27.60% was simulated for FBC-SHJ solar cells featuring localized contacts.

Unidirectional Sidechain Engineering to Construct Dual-Asymmetric Acceptors for 19.23 % Efficiency Organic Solar Cells with Low Energy Loss and Efficient Charge Transfer.

Achieving both high open-circuit voltage (Voc ) and short-circuit current density (Jsc ) to boost power-conversion efficiency (PCE) is a major challenge for organic solar cells (OSCs), wherein high energy loss (Eloss ) and inefficient charge transfer usually take place. Here, three new Y-series acceptors of mono-asymmetric asy-YC11 and dual-asymmetric bi-asy-YC9 and bi-asy-YC12 are developed. They share the same asymmetric D1 AD2 (D1 =thieno[3,2-b]thiophene and D2 =selenopheno[3,2-b]thiophene) fused-core but have different unidirectional sidechain on D1 side, allowing fine-tuned molecular properties, such as intermolecular interaction, packing pattern, and crystallinity. Among the binary blends, the PM6 : bi-asy-YC12 one has better morphology with appropriate phase separation and higher order packing than the PM6 : asy-YC9 and PM6 : bi-asy-YC11 ones. Therefore, the PM6 : bi-asy-YC12-based OSCs offer a higher PCE of 17.16 % with both high Voc and Jsc , due to the reduced Eloss and efficient charge transfer properties. Inspired by the high Voc and strong NIR-absorption, bi-asy-YC12 is introduced into efficient binary PM6 : L8-BO to construct ternary OSCs. Thanks to the broadened absorption, optimized morphology, and furtherly minimized Eloss , the PM6 : L8-BO : bi-asy-YC12-based OSCs achieve a champion PCE of 19.23 %, which is one of the highest efficiencies among these annealing-free devices. Our developed unidirectional sidechain engineering for constructing bi-asymmetric Y-series acceptors provides an approach to boost PCE of OSCs.

Unidirectional Sidechain Engineering to Construct Dual‐Asymmetric Acceptors for 19.23 % Efficiency Organic Solar Cells with Low Energy Loss and Efficient Charge Transfer

AbstractAchieving both high open‐circuit voltage (Voc) and short‐circuit current density (Jsc) to boost power‐conversion efficiency (PCE) is a major challenge for organic solar cells (OSCs), wherein high energy loss (Eloss) and inefficient charge transfer usually take place. Here, three new Y‐series acceptors of mono‐asymmetric asy‐YC11 and dual‐asymmetric bi‐asy‐YC9 and bi‐asy‐YC12 are developed. They share the same asymmetric D1AD2 (D1=thieno[3,2‐b]thiophene and D2=selenopheno[3,2‐b]thiophene) fused‐core but have different unidirectional sidechain on D1 side, allowing fine‐tuned molecular properties, such as intermolecular interaction, packing pattern, and crystallinity. Among the binary blends, the PM6 : bi‐asy‐YC12 one has better morphology with appropriate phase separation and higher order packing than the PM6 : asy‐YC9 and PM6 : bi‐asy‐YC11 ones. Therefore, the PM6 : bi‐asy‐YC12‐based OSCs offer a higher PCE of 17.16 % with both high Voc and Jsc, due to the reduced Eloss and efficient charge transfer properties. Inspired by the high Voc and strong NIR‐absorption, bi‐asy‐YC12 is introduced into efficient binary PM6 : L8‐BO to construct ternary OSCs. Thanks to the broadened absorption, optimized morphology, and furtherly minimized Eloss, the PM6 : L8‐BO : bi‐asy‐YC12‐based OSCs achieve a champion PCE of 19.23 %, which is one of the highest efficiencies among these annealing‐free devices. Our developed unidirectional sidechain engineering for constructing bi‐asymmetric Y‐series acceptors provides an approach to boost PCE of OSCs.

Region-wise and state-wise synthesis of vehicular emissions in India and their mitigation due to vehicular emissions standards

The implementation of different stages of Bharat Stage Emission standards (BSES) in India for reducing the vehicular emissions has been in different parts of the country at various points of time. A quantitative assessment of the emission standards in mitigating vehicular emissions at different Indian states will provide an estimate of achievable emissions standards for future norms. In this regard, the present work reports an assessment of the BS standards – BS-III, BS-IV and BS-VI in reducing the exhaust emissions in each of the Indian states. The assessment is performed through the survival fraction of the vehicles registered with different norms in the two age groups 2013–2017 and 2018–2022 and the corresponding emissions of NOx, CO, VOC, PM2.5 and BC. Over the years 2013–2022, the NOx emissions are the major contributors of vehicular emissions in all the states studied. Surprisingly, the BS-IV vehicles contributed significantly to vehicular emissions in particular states when compared to the BS-III vehicles. This urged to analyse the impact of meteorological and topographical factors on the vehicular emissions. The results revealed that the vehicular emissions are largely dependent on the temperature and altitude and with an increase in temperature and at high altitudes, the CO and VOC emissions are predominant, even in regions with low vehicle population. This finding therefore indicates that the emission limits are not the same for all over the country and meteorology dependent emission limit should be included in framing the vehicle emission norms.

Amplifying the photovoltaic properties of phenylene dithiophene core based non-fused ring by engineering the terminal acceptors modification to enhance the efficiency of organic solar cells

In this study, a series of eight non-fused rings-based semiconducting acceptors (AR1-AR8) were computationally developed by making modifications to the parent molecule (PTICO). In this study, a DFT analysis was conducted at an accurately chosen level of theory to gather a comprehensive inventory of the optoelectronic characteristics of AR1-AR8 and PTICO. The findings indicate that all recently developed molecules exhibit a bathochromic shift in their maximum UV–visible absorbance (λmax) with a smaller band gap (Eg). AR1 has demonstrated the most significant red shift in UV–visible absorbance and possesses the smallest Eg when compared to other recently developed acceptors. AR2 acceptor has shown the best results both as electron and hole-transporting materials owing to its smallest value of reorganization energy for electrons and holes. J61 donor was engaged to calculate the open-circuit voltage (VOC) and the highest VOC with maximum FF % value was observed in AR4. The investigation of charge transfer was also conducted utilizing J61 in conjunction with the AR4 acceptor. Natural transition orbitals (NTO) have also been inspected to recognize the percentage electron transport contribution (% ETC) from the ground state to the first excites state (S0 to S1). The findings of this research suggest that the modified acceptors exhibit potential for practical implementation in the development of organic solar cells that possess improved photovoltaic performance.

Inverted Wide-Bandgap 2D/3D Perovskite Solar Cells with >22% Efficiency and Low Voltage Loss.

Wide-bandgap perovskites play a key role in high-performance tandem solar cells, which have the potential to break the Schockley-Queisser limit. Here, a 2D/3D hybrid wide-bandgap perovskite was developed using octane-1,8-diaminium (ODA) as spacer. The incorporation of the ODA spacer can not only significantly reduce charge carrier nonradiative recombination loss but also inhibit phase separation. Moreover, with a synergy effect using butylammonium iodide (BAI) as a surface defect passivator, both the phase stability and device performance were further improved. Compared to the control inverted device with a VOC of 1.16 V and a PCE of 18.50%, the optimized PSCs based on a surface processed 2D/3D perovskite exhibit a superior high VOC of 1.26 V and a champion PCE of 22.19%, which is a record efficiency for wide-bandgap PSCs (Eg > 1.65 eV). This work provides a very effective strategy to suppress phase separation in wide-bandgap perovskites for highly efficient and stable solar cells.

Experimental Discussion on the Cultivation of Students’ Social Adaptation Ability through Higher VOC

Experimental Discussion on the Cultivation of Students’ Social Adaptation Ability through Higher VOC

Dependence of CZTS thin film properties and photovoltaic performance on heating rate and sulfurization time

In this study, effect of heating rate and sulfurization time on the properties of CZTS thin films and their photovoltaic performances was investigated. CZTS layers were prepared by a two-stage technique comprising deposition of precursor films by sputtering on Mo-foil substrates (Mo-foil/ZnS/CuSn/Cu) and a sulfurization process utilizing Rapid Thermal Annealing (RTA) approach. Heating rates and sulfurization times at 550 °C were changed to determine the best conditions. CZTS films were characterized by several techniques. All samples showed Cu-poor and Zn-rich chemical composition regardless of the heating rate and annealing time of the sulfurization process. XRD diffraction patterns showed that only kesterite CZTS phase was formed in all samples. Although Raman spectroscopy measurements confirmed formation of kesterite CZTS phase in all samples, forming of Cu2SnS3 (CTS) secondary phase was detected in all films except for the sample prepared utilizing a relatively low heating rate of 1 °C/s and 60 s sulfurization time (CZTS-I-60). The largest crystallite size and the less micro strain and dislocation density were also found in this sample. All CZTS thin films displayed dense and compact polycrystalline surface microstructure. Optical characterizations showed that the optical band gaps of the films were in the range of 1.48–1.58 eV. PL emission spectra of the films exhibited transition from conduction band to acceptor/defect levels instead of band-to-band transition. Solar cells were fabricated and the highest Voc and conversion efficiency (4.39%) were achieved employing the film obtained with ramp rate of 1 °C/s and the sulfurization time of 60 s, because of better structural properties and purer crystal structure determined for this sample.

Probing the Effect of Photovoltaic Material on Voc in Ternary Polymer Solar Cells with Non-Fullerene Acceptors by Machine Learning.

The power conversion efficiency (PCE) of ternary polymer solar cells (PSCs) with non-fullerene has a phenomenal increase in recent years. However, improving the open circuit voltage (Voc) of ternary PSCs with non-fullerene still remains a challenge. Therefore, in this work, machine learning (ML) algorithms are employed, including eXtreme gradient boosting, K-nearest neighbor and random forest, to quantitatively analyze the impact mechanism of Voc in ternary PSCs with the double acceptors from the two aspects of photovoltaic materials. In one aspect of photovoltaic materials, the doping concentration has the greatest impact on Voc in ternary PSCs. Furthermore, the addition of the third component affects the energy offset between the donor and acceptor for increasing Voc in ternary PSCs. More importantly, to obtain the maximum Voc in ternary PSCs with the double acceptors, the HOMO and LUMO energy levels of the third component should be around (-5.7 ± 0.1) eV and (-3.6 ± 0.1) eV, respectively. In the other aspect of molecular descriptors and molecular fingerprints in the third component of ternary PSCs with the double acceptors, the hydrogen bond strength and aromatic ring structure of the third component have high impact on the Voc of ternary PSCs. In partial dependence plot, it is clear that when the number of methyl groups is four and the number of carbonyl groups is two in the third component of acceptor, the Voc of ternary PSCs with the double acceptors can be maximized. All of these findings provide valuable insights into the development of materials with high Voc in ternary PSCs for saving time and cost.

Metamorphic front- and rear-junction 1.7 eV GaInP solar cells with high open-circuit voltage

1.7 eV absorber materials are important in high-performance III-V multi-junction solar cells. Here, we show that rapid thermal annealing significantly improves the carrier lifetimes in lightly doped metamorphic 1.7 eV Ga0.37In0.63P (MM GaInP) grown on GaAs by molecular beam epitaxy. A low threading dislocation density of ∼6 × 105 cm−2 was achieved through the use of an InxGa1-xAs graded buffer. Annealing enables minority carrier lifetimes in 1.7 eV p- and n-GaInP of 3.9 and 28 ns, respectively, both of which are higher than annealed lattice-matched 1.9 eV Ga0.51In0.49P (LM GaInP) grown in the same chamber. With the benefit of annealing, MM 1.7 eV GaInP front-junction solar cells show a high peak internal quantum efficiency of 94.3% and an open-circuit voltage (VOC) of 1.17 V. We also demonstrate the first MM 1.7 eV GaInP rear-heterojunction cells with high fill factor and VOC of 85% and 1.21 V, respectively, by taking advantage of long carrier lifetime while eliminating majority carrier blocking. The high VOC values for the 1.7 eV GaInP cells presented in this work indicate promising tolerance to threading dislocations in MM GaInP.

Impact of symmetry breaking on the performance of non-fullerene acceptors (NFAs) for photo and thermally stable organic solar cells (OSCs): A DFT-based interrogation and investigation

Simultaneous enhancement in the fill factor (FF) and power conversion efficiency (PCE) is a crucial task for the development of photovoltaic (PV) devices. In addition, symmetrical acceptor molecules lack photo and thermal stability due to low extinction coefficient and dipole moment. Breaking of symmetry in typical fullerene-free acceptors brings high values of dipole moments along with crystalline features. In this regard, a series of new acceptor molecules have been designed by deep end-capped remodeling of the IPC-BEH-IC2F. Newly remodeled systems disclosed high values of electronic charge shifting and perfect molecular packing. The impact of symmetry breaking is examined through density functional theory (DFT) and time-dependent density functional theory (TDDFT) at CAM-B3LYP/6-311G(d,p) level. Photovoltaic and geometric aspects like frontier molecular orbitals (FMOs), excitation energy, open circuit voltage (Voc), FF%, and PCE have been computed theoretically. Reshaped systems expressed high mobilities of the electrons and holes towards the metal electrodes together with easy excitation of the exciton. High Voc enhances the FF% and PCE in the SGS-1 to SGS-4. Results of all analyses showed that SGS-1 to SGS-4 are well-designed systems for the development of the highly efficient active layer for OSCs.

Machine learning, experiments and molecular simulation demonstrate the adsorption mechanism of acetone on porous carbon at different pressures

The scientific design and preparation of porous carbon with high VOCs (such as acetone) adsorption capacity are crucial for waste gas treatment. However, it is still challenging to explain the microscopic mechanism of acetone uptake on porous carbon because of the different adsorption conditions, as well as various chemical properties and different pore structures of porous carbon. Here, the prediction model of the adsorption conditions, nitrogen/oxygen groups and pore structures on acetone adsorption capacity was established by machine learning, and the contribution of the nitrogen/oxygen groups and pore structures of porous carbons to the acetone adsorption capacity at different adsorption pressures was discussed. The results display that the nitrogen/oxygen groups and micropore volume are the main factors affecting the adsorption capacity of acetone at relatively low pressure, while the adsorption capacity at relatively high pressure is determined by total pore volume. Subsequently, three kinds of porous carbon with different oxygen content and gradient pore size distribution were synthesized, and acetone adsorption isotherms were tested. The effects of chemical properties and pore structure on acetone adsorption at different pressure were studied, and the results were consistent with those of machine learning. However, the results are challenging to illustrate the effect of single pore size and functional group type on acetone adsorption performance. Finally, molecular simulation was used to calculate acetone adsorption isotherms with various nitrogen/oxygen groups and different pore sizes, further revealing the adsorption mechanism of acetone with nitrogen/oxygen groups and pore size. Based on machine learning and molecular simulation results, new insights into the adsorption behavior of acetone were revealed, providing theoretical support for the sustainable development of carbon-based adsorbents for acetone waste gas treatment.

Engineering push–pull structural versatility in highly functional carbazole-based hole transporting materials design for efficient perovskites solar devices

This study proposes a push–pull molecular engineering strategy to design highly functional hole transport materials (HTMs) for perovskite solar cells (PSCs). The strategy involves introducing acceptor-anchor groups via benzene spacer to the versatile carbazole core containing dimethoxytriphenylamine side groups, resulting in a series of nine newly designed HTM moieties (BEN-A1 to BEN-A9). Quantum simulation protocols using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) methods were employed to investigate the designed HTMs. Our results demonstrate that the designed HTMs exhibit promising charge separation and transport throughout the molecule with lower spatial hole-electron overlap at the carbazole core, resulting in 98% intrinsic charge transfer and small exciton binding energy (0.003–0.108 eV). The HTMs also exhibit stabilized HOMO energy levels (by up to 0.13 eV) approaching the threshold (−5.38 eV) with appropriate HTM/Perovskite energy levels alignment, suggesting excellent charge extraction and higher VOC. Optical analysis shows that our proposed HTMs exhibit large stokes shift values (82–108 nm) and transparent absorption in broader visible region, enabling full utilization of light for perovskite layer for photocurrent generation, efficient energy conversion, reduced thermalization losses, and improved spectral selectivity. The HTMs exhibit smaller hole reorganization energy (0.111–0.137 eV) and higher transfer integral, indicating robust hole mobility owing to enhanced carbazole core functionality. Furthermore, higher negative solvation-free energy values (−16.19 to −20.89 kcal/mol) and elevated dipole moments imply better solubility and surface-wetting properties. Overall, this study broadens our understanding of push–pull molecular engineering for versatile carbazole-based HTMs, which have immense prospects for efficient and functional application in PSCs.