Power Conversion Efficiency Research Articles

An investigation on the impact of temperature variation over the performance of formamidinium tin iodide perovskite solar cell using SCAPS simulation

The primary goals of this project are to analyze the structure and assess the photovoltaic performance of n-i-p structured formamidinium tin iodide (FASnI3) perovskite solar cells at different operating temperatures to inspect the impact of operating temperature on device performance using a Solar Cell Capacitance Simulator (SCAPS). The simulated device structure is Au/spiro-OMeTAD/P3HT/FASnI3/PCBM/TiO2/FTO, whereas spiro-OMeTAD and TiO2 serve as the hole transport layer and electron transport layer, respectively. SCAPS simulation has been performed at 200, 300, 400, 500, and 600 K operating temperatures, and corresponding current density vs voltage (J–V) characteristics have been studied in addition to the photovoltaic metrics, such as open circuit voltage (VOC), short circuit current density (JSC), fill factor (FF), and power conversion efficiency (PCE). The thickness fluctuation and doping concentration variation of the absorber layer and the electron affinity variation and thickness variation of the Hole Transport Layer (HTL) and Electron Transport Layer (ETL) under temperature variation were also examined analytically. It has been found that there is an inverse relationship between temperature and power conversion efficiency (PCE). The extended thickness of the absorber layer enhances the PCE and JSC. Temperature variations in the thickness of the ETL and HTL have a minimal effect on the PCE and JSC of the device. At standard room temperature (300 K operating temperature), the solar cell parameters are found to be a short-circuit current density (JSC) of 17.93 mA/cm2, open-circuit voltage (VOC) of 1.06 V, fill factor (FF) of 67.46% and power conversion efficiency (PCE) of 17.93%.

Facet orientation control of tin-lead perovskite for efficient all-perovskite tandem solar cells

Developing high-performance narrow-bandgap (NBG) perovskite solar cells based on tin-lead (Sn-Pb) perovskite is critical for the advancement of all-perovskite tandem solar cells. However, the limitation of the device current density and efficiency is magnified by the issues concerning poor carrier transport caused by a substantial number of defects in thick NBG films. This problem is further exacerbated by the quality of film crystallization, which is associated with the rapid and uncontrolled crystallization of Sn-rich perovskite chemistry using the antisolvent approach. We regulate the crystallization of Sn-contained perovskite with a mild gas-quench approach to fabricate a highly crystal-oriented and well-arranged NBG perovskite absorber. This strategy effectively boosts electron transport and light absorption of the NBG perovskite. Consequently, the average power conversion efficiency (PCE) of the NBG perovskite solar cells increases from 19.50% to 21.18%, with the best device achieving an excellent PCE of 21.84%. Furthermore, when combined with a wide-bandgap perovskite subcell to form an all-perovskite tandem solar cell, a PCE of 25.23% is achieved. After being stored in the glovebox for 1000 h, the unencapsulated device maintains over 90% of its initial PCE, demonstrating long-term stability and durability. This work presents a promising approach for developing high-efficiency NBG perovskite solar cells.

Highly Stable Two-Dimensional Janus MXY-Based van der Waals Heterostructures for Exceptional Solar Cell Performance

The development and utilization of solar energy are extremely important for alleviating energy and environmental problems. Herein, we comprehensively fabricated a series of two-dimensional Janus MXY-based van der Waals heterostructures (M=Mo, W; X, Y=S, Se, Te, and X≠Y) and thoroughly investigated their potential applications in solar cells using first-principles density functional theory. Further analysis identifies 20 heterostructures with power conversion efficiencies (PCEs) exceeding 20%. Additionally, the impact of spin-orbit coupling (SOC) effects and intrinsic dipole correction on band structures and PCEs is examined. Particularly noteworthy are the WSSe/WSeTe SeSe BB and WSeTe/WSTe TeTe BB' vdWHs, exhibiting superior PCEs of 19.25% (23.51%) and 21.53% (20.49%) with (without) SOC effects and dipole correction, alongside minimal exciton binding energies (0.36 eV and 0.32 eV), excellent stability, and high light absorption coefficients (105∼106 cm−1). These outstanding values surpass most reported results. These findings underscore the potential of Janus TMD vdWHs, particularly WSSe/WSeTe SeSe BB and WSeTe/WSTe TeTe BB' configurations, for advanced solar cell applications, offering valuable theoretical insights for future experimental investigations.

Improving the efficiency above 35% of MoS2-based solar cells by through optimization of various wide-bandgap S-chalcogenides ETL

Molybdenum disulfide (MoS2)-based photovoltaic cells are increasingly attracting researchers’ due to their outstanding semiconducting properties. Single junction MoS2 based solar cell have been investigated with three distinct electron transport layer (ETL) layers made of SnS2, In2S3 and ZnSe in detail with and without back surface field (BSF). A thorough numerical analysis has been conducted of the effects of band alignment, defect density, absorber layer thickness, buffer layer thickness, interface defect density, electron and hole concentration, generation and recombination, open circuit voltage (VOC), short circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE) via SCAPS-1D simulation software. The MoS2 based solar cell produced the photo conversion efficiency (PCE) of 24.77% with VOC of 0.913 V, JSC of 31.274 mA/cm2, and FF of 86.77% without BSF. On the other hand, after in depth analysis, according to simulation results, SnS2 ETL produced the highest PCE of 35.60% than ZnSe(33.56%) and In2S3(34.94%) ETL with VOC of 1.07 V, JSC of 37.55 mA/cm2, and FF of 88.80% with inserting only 30 nm V2O5 BSF layer. The suggested research might provide information and a workable strategy for producing a MoS2-based thin-film solar cell that is affordable.

The significance of bilayer window (CdS:O/CdS) on the performance of CdTe thin film solar cells

Ultrathin and compact CdS:O/CdS bilayer window in CdTe solar cells has higher potential for enhanced p-type doping, reduced Te diffusion, and improved power conversion efficiency (PCE) compared to traditional single-layer CdS or CdS:O windows. In this effort, we used a two-gun RF sputtering equipment to deposit compact CdS:O(∼50 nm)/CdS(∼50 nm) bilayers onto the borosilicate and ITO-coated glass substrates at low temperature (≤ 250 oC). Intriguingly CdS:O/CdS bilayers retain its hexagonal {0002} preferential orientation but with around 10.58% optical bandgap (Eg) increment compared to CdS (Eg≈2.32 eV) of equal thickness (∼100 nm). Close-spaced sublimation (CSS) technique was used to deposit the CdTe thin film onto the CdS and CdS:O/CdS layers at 550 °C. The effect of CdS and CdS:O/CdS layers on the microstructural and morphological features of CdCl2-treated CdTe films were critically analyzed revealing a promising {0001}/{111}-like partial-epitaxy presumably due to the preferential cubic CdTe growth along the <111> orientation. The CdTe films grown over a CdS:O/CdS layer exhibited smaller average crystallite and grain sizes than those grown over a single CdS layer. An essential finding was the formation of an optimal intermix layer of CdSxTe1-x, particularly evident in the CdTe films grown on the CdS:O/CdS bilayer. To comprehensively explore the effect of CdS:O/CdS window layers on PCE, complete CdTe solar cells were fabricated using three different window layers: CdS, CdS:O, and CdS:O/CdS, which are all considered as rudimentary as no layer optimization was performed. Notably, CdTe solar cell that incorporates the CdS:O/CdS bilayer window exhibited the most promising performance among all the tested rudimentary cells and corroborated the numerically simulated findings conducted by the SCAPS-1D simulator.

Highly electronegative additives suppress energetic disorder to realize 19.19 % efficiency binary organic solar cells

Additive engineering plays an important role in realizing high efficiency organic solar cells (OSCs). The introduction or residual of additives usually increases the energetic disorder of the active layer, which in turn causes a significant reduction of the open-circuit voltage (VOC). Herein, this work proposes a novel additive design approach, that is, using the highly electronegative groups trifluoromethyl and trifluoromethoxy to replace one bromine atom of 1,3,5-tribromobenzene (TBB) to obtain 3,5-Dibromobenzotrifluoride (DBTF) and 3,5-Dibromo-triffluoromethoxybenzene (DBOF). This series of additives can induce strong π-π coupling with acceptor, modulating molecular crystallization and orderly stacking, and thus reducing the non-radiative energy loss and energetic disorder of the OSCs. Furthermore, DBTF and DBOF have good volatility and can be removed from the active layer without any post-processing. Consequently, a high power conversion efficiency (PCE) of 18.78 % is obtained in D18: Y6-based OSCs and a remarkable PCE of 19.19 % is realized in D18-Cl/ Y6-based OSCs. Compared with the OSCs without or with conventional TBB additives, the DBOF-treated OSCs effectively suppress the reduction of VOC while enhancing PCE. This work provides guidance for the design and synthesis of additives with selectivity, auto-removability, and the ability to reduce the energetic disorder of the OSCs.

Small molecule perylene diimide derivatives with different bay site modifications as cathode interface layers for organic solar cells

Cathode interface layers (CILs) can effectively elevate the performance of organic solar cells (OSCs), and the development of CILs with high thickness insensitivity is the focus of commercializing OSCs. PDI derivatives proved to be potential CILs, and bay modification could further adjust the coplanarity and optimize the film-forming properties of PDI-based CILs. Thus, two novel CILs with intermediate-sized spacer groups were synthesized (PDINN-P3P and PDINN-TPA). In contrast to PDINN-P3P with m-diphenylbenzene, PDINN-TPA with triphenylamine can form stronger self-doping between the side chain of triphenylamine and the PDI backbone, resulting in higher charge transport capacity and better interface regulation ability. PDINN-TPA-based OSCs demonstrated a higher power conversion efficiency (PCE) of 16.11 % in the PM6:Y6 system, outperforming the PCE of PDINN-P3P-based OSCs (15.00 %). Meanwhile, PDINN-TPA expressed a favorable thickness processing range, a PCE of 14.19 % can be maintained with a thickness up to 35 nm. After storing in the glove box for 114 h, PDINN-TPA-based OSCs can exhibit excellent long-term stability (over 90 % of the optimal PCE). Besides, PDINN-P3P and PDINN-TPA were further utilized CILs in the PM6: BTP-eC9 system, and the PDINN-TPA-based OSCs acquired a PCE of 16.91 % (15.54 % for PDINN-P3P-based OSCs), highlighting the broad applicability of PDINN-P3P and PDINN-TPA. This study confirms that the synergistic effect of bay site modification and n-type self-doping on PDI can simultaneously optimize the thickness insensitivity and long-term stability of PDI-based CILs.

Enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a dye sensitizer for dye-sensitized solar cells (DSSCs) through the incorporation of electron donor moieties

This study has focused on enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a sensitizer for dye-sensitized solar cells (DSSCs) by strategically incorporating electron donor moieties identified in a literature review. Our reviewing the previous reports highlights the pivotal role of electron donors in optimizing light harvesting, electron injection, and overall power conversion efficiency in organic dye sensitizers, particularly those following a donor-bridge-acceptor (D-π-A) architecture. The selected donor moieties, including dithieno[3,2-b:2′,3′-d]thiophene (DTT), benzodithiophene (BDT), triphenylamine (TPA), carbazole (CBZ), and triazatruxene (TAZ), are systematically introduced into the molecular structure of PCC (abbreviated as PCC-DTT, PCC-BDT, PCC-TPA, PCC-CBZ, and PCC-TAZ, respectively). The performance of these modified compounds is rigorously evaluated using density functional theory (DFT) methods. Validation results revealed that the most reliable method for PCC derivative characterization involved the combination of the functional B3PW91 with a 6-31G(d) basis set. The results indicate that the incorporation of certain donor moieties, particularly BDT, significantly enhances the electronic and optical properties of PCC, including lower HOMO energy levels, a narrow energy gap (Egap), enhanced absorption intensity, and a redshift in absorption peaks. Evaluation of photovoltaic properties including electron injection (ΔGinj), and open circuit voltage (Voc), indicated facilitating spontaneous electron injection from the dyes to the TiO2 conduction band. Notably, PCC-TAZ demonstrated the lowest electron regeneration (ΔGreg), suggesting a notable potential for efficient electron regeneration.

Double-bridged N–B←N bipyridyl-based airfoil-shaped small molecule dyes: π-bridge regulation on photovoltaic performance

The double-bridged N–B←N bipyridine unit (BNBP) with boron-nitrogen covalent bond and coordination bond can reduce the electronic energy level of the π-conjugated system, resulting in a reduction of band gap and a red shift in the absorption spectrum. Embedding the BNBP building block into organic optoelectronic materials provides a novel possibility in molecule design. In this paper, under the guidance of density functional theory (DFT) calculations, a series of 3D “airfoil-shaped” small molecule donors (SMDs) have been designed and successfully synthesized through Sonogashira, Suzuki and Stille coupling reactions. BNBP is adopted as the central electron-withdrawing unit and strong electron-rich triphenylamine (TPA) as the terminal group. The novel “airfoil-shaped” structure plays a supporting role in reducing the carrier recombination in the active layer. It reveals that molecular design engineering can achieve the expected results by the following steps: Firstly, the introduction of electron-rich alkoxy groups into the end of TPA through side chain engineering helps to improve the solubility and film-forming properties of the materials. Then, the π-bridge regulation not only extends the conjugate structure, but also plays a crucial role in the regulation of photovoltaic properties. It is worth noting that the compound BNBP(3TTPA)2 was synthesized by introducing thiophene oligomer into BNBP-based SMDs for the first time. Finally, the compound BNBP(EDPPTPA)2 was constructed by combining BNBP with DPP dye unit. Its narrow band gap is only 1.36 eV, which is one of the narrowest band gaps in small molecular organic-boron materials. In particular, compared with the starting compound BNBP(ETPA)2, the synergistic effects of DPP and BNBP broaden the edge absorption wavelength to 814 nm, resulting in a red shift of 170 nm. The power conversion efficiency (PCE) of 4.48 % is obtained in BNBP(EDPPTPA)2-based bulk heterojunction (BHJ) organic solar cells (OSCs), which is more than twice that of reference compound BNBP(ETPA)2. This work provides important references for the future development of 3D BNBP-based organic-boron SMDs and the structural regulation of materials through molecular engineering.

An analysis comparing the performance of lead and tin halides organic Perovskite Solar Cells and numerical simulation with SCAPS.

The scientific community focused on finding environmentally safe alternative metal halides to address the instability and toxicity associated with lead perovskite materials. These alternatives are supposed to replace lead halides without altering the distinctive properties of lead perovskite materials. Additionally, they should contribute to producing longer-lasting and stable perovskite in solar cells. This research presents a practical investigation of using tin- and lead-based composites in perovskite iodide solar cells with Titanium dioxide (TiO2) and Copper oxide (CuO) as electron transport materials (ETM) and hole transport materials (HTM), respectively. The performance parameters of the perovskite solar cells (PSCs) are compared with those of lead-based and lead-free PSCs with the same charge transport layers of ETM and HTM, as well as compare the practical results with the software results of Solar Cell Capacitance Simulation (SCAPS) package. In this study, the performance of PSCs with an absorption layer ((CH3NH3PbI3)t / (CH3NH3SnI3)1-t) was examined. The thickness of the perovskite layer is represented by (t), which can take the values( t = 1, 0.5, or 0) μm. The results of the laboratory study were compared to the performance of PSCs based on numerical analysis of SCAPS modeling. PSCs were prepared with a configuration structure (FTO / compact TiO2 / (CH3NH3PbI3)t/ (CH3NH3SnI3)1-t /CuO /Cu-electrode). A tetragonal phase was obtained for perovskite materials CH3NH3PbI3 and CH3NH3SnI3 with a direct optical energy gap estimated at (1.55 and 1.35) eV, respectively. The l-V curve of the prepared PSCs was studied, and the performance of the solar cells was examined under a light intensity of 100 mW/cm2. The power conversion efficiency, PCE, of the prepared solar cells, was (PCE = 2.9, 3.11, or 0.5) at (t = 1, 0.5, or 0)μm, respectively. A comparative analysis was also performed between the empirical performance of the manufactured PSCs and the theoretical results acquired by the SCAPS package software.

Prediction of the photovoltaic performance of the lead-free layered Ruddlesden–Popper organic–inorganic perovskite (CH3NH3)2GeI4

Using the density functional theory (DFT) and the spectral limited maximum efficiency (SLME) model, we thoroughly evaluate the material MA2GeI4 as a prospective absorber for photovoltaic applications. This material belongs to the family of layered material organic-inorganic Ruddlesden-Popper perovskites, which have attracted interest due to their stability. Our first-principles calculations show that MA2GeI4 has a direct bandgap that is suitable for light absorption at 1.37 eV. To understand the source of its exceptional optical properties, the electronic structure, density of states, and optical properties were examined. Also, we used the SLME model to estimate the MA2GeI4 solar cell efficiency. The latter was found to be about 32.6% power conversion efficiency. The material’s excellent absorption and promising photovoltaic properties contribute to its high efficiency, even when quantum confinement occurs between layers. We found that MA2GeI4 is a potential absorber material for solar applications, demonstrating both good absorption characteristics and advantageous electrical properties. This discovery lays the path for additional experimental investigation of MA2GeI4 based solar cell.

DFT simulations of photovoltaic parameters of dye‐sensitized solar cells with new efficient sensitizer of indolo[3, 2‐b]carbazole complexes

AbstractDeveloping economical and high‐performing sensitizers is crucial in advancing dye‐sensitized solar cells (DSSCs) and optoelectronics. This research paper explores the potential of novel red light‐absorbing organic dyes based on Indolo[3,2‐b]carbazole (ICZ) as the donor applied in co‐sensitizer‐free DSSCs for breakthroughs in photovoltaic (PV) applications. DFT and TD‐DFT based computational methods were employed to calculate the conduction band levels, electron injection capabilities, and power conversion efficiency (PCE) of metal‐free organic dyes (ICZ1–ICZ9) having D‐A‐π‐A architecture. Comprehensive analyses included NBO, DOS, FMO, ICT, MEP, binding energy, and TDM analysis. Quantum chemical calculations of the structural, photochemical, and electrochemical properties, as well as the key parameters, reveals that all the designed dyes could be an excellent candidate for high‐efficiency DSSCs due the small energy gap (2.130–1.947 eV), longer wavelength absorption (759.47–520.63 nm), longer lifetimes (15.65–6.67 ns), a lower ΔGreg (0.29–0.14 eV), a significant dipole moment changes (31.489–16.195D), LHE (0.95‐0.46), the large qCT (0.962–0.689), small DCT (7.657, 4.897 Å), and VOC (1.13–0.86 eV). This quantum simulation showed that, when compared to reference D8, the photovoltaic dyes ICZ8, ICZ2, and ICZ7 are recognized as being eye‐catching. Furthermore, dye@(TiO2)9 cluster model results demonstrate promising prospects for enhancing the photovoltaic (PV) performance of ICZ1–ICZ9 dyes by electron injection and conduction band (CB) engineering. This study will help the experimentalists for developing ICZ‐based PVs as more efficient and sustainable energy solutions.

Nanocomposites of Co-NiS/GO as a Versatile Catalyst: Enabling Platinum-Free DSSC Counter Electrodes and Enhancing Organic Dye Degradation

This study presents the synthesis of a nanocomposite intended to serve as a counter electrode in dye-sensitized solar cells (DSSCs), replacing platinum electrodes, as well as functioning as a nanocatalyst for organic dye degradation. Graphene oxide was synthesized using a modified Hummers method, and cobalt-doped nickel sulfide on graphene oxide (Co-NiS/GO) was prepared via hydrothermal synthesis. The samples underwent characterization through various testing methods. X-ray diffraction analysis revealed a hexagonal structure with a crystallite size of 30 nm. Field-emission scanning electron microscopy/energy-dispersive X-ray images showed a cornflake-like structure, with elements such as cobalt, nickel, sulfur, carbon, and oxygen present. Chemical valence states were confirmed through X-ray photoelectron specteroscopy analysis. The power conversion efficiency of the Co-NiS/GO counter electrode in DSSCs was investigated, with parameters such as open-circuit voltage, short-circuit current density, fill factor, and power conversion efficiency calculated to be 8.6032 mV, 0.5484 mA cm−2, 61, and 2.83%, respectively, based on I-V studies. Furthermore, the developed Co-NiS/GO nanocomposite was assessed for its photo catalytic dye degradation capabilities using malachite green (MG), achieving a degradation rate of approximately 96% within 180 min.

Over 18.2% efficiency of layer–by–layer all–polymer solar cells enabled by homoleptic iridium(III) carbene complex as solid additive

The vertical phase distribution of active layers plays a vital role in balancing exciton dissociation and charge transport for achieving efficient polymer solar cells (PSCs). The layer–by–layer (LbL) PSCs are commonly prepared by using sequential spin–coating method from donor and acceptor solutions with distinct solvents and solvent additives. The enhanced exciton dissociation is expected in the LbL PSCs with efficient charge transport in the relatively neat donor or acceptor layers. In this work, a series of LbL all–polymer solar cells (APSCs) were fabricated with PM6 as donor and PY–DT as acceptor, and triplet material m–Ir(CPmPB)3 is deliberately incorporated into PY–DT layer to prolong exciton lifetimes of active layers. The power conversion efficiency (PCE) of LbL APSCs is improved to 18.24% from 17.32% by incorporating 0.3 wt% m–Ir(CPmPB)3 in PY–DT layer, benefiting from the simultaneously enhanced short–circuit current density (JSC) of 25.17 mA cm−2 and fill factor (FF) of 74.70%. The enhancement of PCE is attributed to the efficient energy transfer of m–Ir(CPmPB)3 to PM6 and PY–DT, resulting in the prolonged exciton lifetime in the active layer and the increased exciton diffusion distance. The efficient energy transfer from m–Ir(CPmPB)3 to PM6 and PY–DT layer can be confirmed by the increased photoluminescence (PL) intensity and the prolonged PL lifetime of PM6 and PY–DT in PM6+m–Ir(CPmPB)3 and PY–DT+m–Ir(CPmPB)3 films. This study indicates that the triplet material as solid additive has great potential in fabricating efficient LbL APSCs by prolonging exciton lifetimes in active layers.

Performance optimization of lead-free potassium germanium halide based perovskite solar cells: A numerical study

Conventional lead-halide perovskite solar cells (PSCs) have great potential as top contenders for commercial utilization due to their impressive performance. Nevertheless, the stability issues and undue toxicity have limited their widespread use. Consequently, lead-free germanium-based PSCs have materialized as potential substitutes due to their high working efficiency and exceptional sustainability. The current study has examined various configurations of non-toxic inorganic potassium germanium trichloride (KGeCl3) based PSC structure by using different Hole Transport Layers (HTL) and Electron Transport Layers (ETLs) respectively. This work proposes an efficient Ge-based PSC (structure; FTO/MoO3/KGeCl3/WS2/Au), which has been optimized theoretically using SCAPS-1D. The influence of the material parameters, such as the thickness of the absorber layer (nm), donor density (Nd), acceptor density (Na), absorber defect density(Nt), interface layer defect density (IL1& IL2), series resistance (Rs) and shunt resistance (Rsh), and working temperature (K), has been optimized. The open circuit voltage (Voc), current density (Jsc), fill factor (FF), and power conversion efficiency (PCE) of KGeCl3-based PSC have all been commendably optimized. The results indicated WS2 as the most effective ETL for KGeCl3 with MoO3 as an HTL, yielding notable cell performance with Voc of 0.88 V, Jsc of 41.45 mA/cm2, FF of 81.76 %, and PCE of 29.83 %. The outcomes of this simulation study suggest the utilization of KGeCl3 as the absorber layer, in conjunction with WS2 and MoO3 as advanced ETL and HTL layers, which pays the way for continued development and optimization of Ge-based PSCs for potential applications.

Solid additive enables efficient and stable organic solar cells by stabilizing morphology of active layer

Additive strategy is an effective method for optimizing the morphology of active layer in organic solar cells (OSCs). However, common high boiling points solvent additives may compromise device stability. In this work, 1-bromo-8-chloronaphthalene (BCN) was used as a solid additive to improve device performance. The introduction of BCN promotes the crystallinity, H-aggregation and fibrillation of L8-BO. The active layer film with additive BCN exhibits optimized phase separation and refined fiber network, thus enhancing the exciton dissociation and charge transport in the corresponding devices. Compared with control devices (without additives), the power conversion efficiency (PCE) of optimized devices (with 20 wt% BCN) based on D18:L8-BO was increased from 17.49 % to 18.20 %. The detailed process of device fabrication is in experimental section. Furthermore, devices processed by BCN preserved 96.6 % and 96.3 % of the initial PCE after aging for 60 minutes with maximum power point (MPP) tracking and aging of storage for 960 h, respectively. The universality of BCN was verified in different systems, which offers promising opportunities to regulate BHJ morphology toward highly efficient OSCs.

Photovoltaic performance enhancement via cocktail co-sensitization of D–A–π–A and D–π–A–π–A dyes in dye-sensitized solar cells

A novel organic dye (BIM37) featured with donor–auxiliary acceptor–π–acceptor (D–A–π–A) structure based on an acridine π–bridge has been designed and synthesized for dye-sensitized solar cells (DSSCs). Unlike the acridine-based D–π–A–π–A dyes (BIM25 and BIM26), BIM37 was obtained by inserting an auxiliary acceptor between the donor and π–bridge units. This modification leads to a significant red shift in the absorption spectrum compared to its counterparts. Thus, the DSSCs based on BIM37 achieved a power conversion efficiency (PCE) of 5.03%, which is higher than that of BIM25 (3.76%) or BIM26 (4.56%). To further improve the photovoltaic performance, the cocktail co-sensitization strategy was applied. In the presence of chenodeoxycholic acid (CDCA) as a co-adsorbent, the co-sensitized DSSC based on BIM37+BIM26 showed a high efficiency of 6.30%. This performance is superior to individual DSSCs with and without CDCA. The results show that molecular engineering for co-sensitization may be an effective strategy to improve the performance of DSSCs.

Ternary Polymer Solar Cells Using Two Nonfullerene Acceptors With Cascading Energy Level and Complementary Absorptions

In this paper, we have fabricated ternary PSC with BTP-eC9 as the host acceptor, IT-M as the guest acceptor, and PM6 as donor. The optimized ternary PSC (PM6:BTP-eC9:IT-M ratio is 1:1.2:0.2) has the highest power conversion efficiency (PCE) of 17.06% compared to the PM6:BTP-eC9 binary PSC (16.46%) and PM6:L8-BO reference binary PSC (16.92%). We systematically investigated the effect of blend acceptors on morphology, photovoltaic performance and charge carrier dynamics. After the addition of IT-M to PM6:BTP-eC9 binary film, the highest JSC (from 26.39 to 26.82 mA cm-2) was achieved for optimized ternary PSCs compared to PM6:BTP-eC9 binary PSC, which was attributed to the high efficiency of light absorption in the medium to long-wavelength region of IT-M. Shallower lowest unoccupied molecular orbitals (LUMO) level of IT-M enlarged the optical bandgap, which leads to an increase in the open-circuit voltage (VOC, from 0.86 V to 0.875 V). In addition, a small amount of IT-M improves the surface and bulk morphology and crystallinity of the ternary film. The ternary films shown high charge mobility ability. This work demonstrates that supplementing the light absorption and broadening the optical bandgap of PM6:BTP-eC9 binary films by IT-M as third component can effectively improve the PCE and obtain higher photovoltaic performance than that of PM6:BTP-eC9 binary PSCs and PM6:L8-BO reference binary PSCs.

Wide-bandgap MAPbBr3 perovskite solar cells using bifunctional-molecule additives achieving a high open-circuit voltage of 1.63 V

Wide-bandgap methyl ammonium lead bromide (MAPbBr3) perovskite solar cells (PSCs) attracts considerable attention due to their large open-circuit voltage (VOC), high phase stability and great potential for multi-junction tandem PSCs. However, the low film quality and high defect density of perovskite films limit the development of MAPbBr3 PSCs. Here, we employ a bifunctional-molecule of 3-chlorbenzylamine additive (3-CBA) to fabricate high quality MAPbBr3 films in ambient air and facilitate the crystallization of MAPbBr3 film, leading to higher orientated perovskite film. Additionally, 3-CBA associating with uncoordinated Pb ions effectively passivates the bulk defects, which suppresses the carrier recombination in perovskite films and obtains a high VOC of 1.63 V. To further suppress the carrier recombination at MAPbBr3/carbon interface, the 3-CBA is also used to modify the surface of the MAPbBr3 films. As a result, the 3-CBA modified MAPbBr3 film exhibits decreased roughness and increased coverage on substrates, which raises the power conversion efficiency (PCE) to 9.55 %. More importantly, the chlorphenyl in 3-CBA for both bulk and surface treatment makes the MAPbBr3 surface more hydrophobic, which enhances the stability of unencapsulated PCSs allowing it to maintain over 98 % of the initial PCE under 80 °C thermal stress and 40–70 % relative humidity. This work provides a reliable approach to enhance both the VOC and stability for MAPbBr3 wide-bandgap PSCs.

Dandelion-like VSe2-embellished CuSe-Co3Se4 hollow nanotube clusters as bifunctional catalysts for high-performance alkaline hydrogen evolution and solar cells

Among the various non-precious metal catalysts that drive hydrogen evolution reactions (HERs) and dye-sensitized solar cells (DSSCs), transition metal selenides (TMSs) stand out due to their unique electronic properties and tunable morphology. Herein, the multicomponent selenide CuSe-Co3Se4@VSe2 was successfully synthesized by doping with metal element vanadium and selenization on the copper-cobalt carbonate hydroxide (CuCo-CH) template. CuSe-Co3Se4@VSe2 exhibited the dandelion-like cluster structure composed of hollow nanotubes doped with VSe2 nanoparticles. Due to the unique structure and the synergistic effect of various elements, CuSe-Co3Se4@VSe2 showed excellent alkaline HER and DSSC performances. The DSSC based on CuSe-Co3Se4@VSe2 exhibited an impressive power conversion efficiency (PCE) of 9.64 %, which was much higher than that of Pt (8.39 %). Besides, it possessed a low HER overpotential of 76 mV@10 mA cm−2 and a small Tafel slope of 88.9 mV dec−1 in 1.0 M KOH.