Short-circuit Current Density Research Articles

Thymus schimperi Ronniger plant flower extract dye-sensitized solar cells

The demand for energy is greatly increasing due to the world’s population growth and technological advancement. Natural dye-sensitized solar cells are attracting research as an alternative and renewable energy source due to their simple preparation technique, availability, cost effectiveness and environmental friendliness. In the present work, we have successfully fabricated dye-sensitized solar cells (DSSCs) from Thymus schimperi Ronniger plant flowers for the first time. The solvents used for extraction of the flower dye were deionized water and its mixture with ethanol. The T. schimperi Ronniger flower extract dye solutions and sensitized photoanodes were characterized by Fourier transform infrared and ultraviolet–visible techniques. The crystallinity of TiO2 films was analyzed by x-ray diffraction, and the films showed pure anatase phase behavior. The photoelectrochemical solar cell performance parameters, such as short circuit current density, open circuit voltage, fill factor and efficiency, were evaluated from current density–voltage measurements using a Keithley 2450 source meter. DSSCs sensitized with dye solution extracted by a mixture of water and ethanol showed better performance (1.37%) than those sensitized with dye solution extracted by deionized water alone (1.02%).

Predicting photovoltaic parameters of perovskite solar cells using machine learning

Perovskite solar cells (PSCs) have garnered significant attention owing to their highly power conversion efficiency (PCE) and cost-effectiveness. Traditionally, screening for PSCs with superior photovoltaic parameters relies on resource-intensive trial-and-error experiments. Nowadays, time-saving machine learning (ML) techniques serve as an artificial intelligence approach to expedite the prediction of photovoltaic parameters using accumulated research datasets. In this study, we employ seven supervised ML methods to forecast key photovoltaic parameters for PSCs such as PCE, short-circuit current density (J sc), open-circuit voltage (V oc), and fill factor (FF). Particularly, we design an artificial neural network (ANN) architecture that incorporates residual connectivity and layer normalization after the linear layers to enhance the scope and adaptability of the network. For PCE and J sc, ANN demonstrates superior prediction accuracy, yielding root mean square errors of 2.632% and 2.244 mA cm−2, respectively. The Random Forest (RF) model exhibits exceptional prediction performance for V oc and FF. Additionally, an interpretability analysis of the model is conducted to elucidate the impact of features on PCE prediction, offering a novel approach for accurate and interpretable ML methods in the context of PSCs.

Characterization of graphene–TiO2-deposited semi-organic solar cell

High energy supply is critical, particularly in developing countries, to maintain lifestyles as the world's population and technological-economic metropolis grow. Solar photovoltaic cells have been used as an alternative to generate renewable, sustainable, and green energy for the past two decades. In general, the materials employed in the photoanode part are critical to manufacturing high-efficiency solar cells with 14–18% efficiency. A simple and successful method has been discovered for creating a film composed of graphene sheets and 99.8% pure anatase titanium oxide (TiO2) nanoparticles. After sensitization, the films were tested as photoelectrodes for dye-sensitized solar cells. The experimental results show that using an optimized graphene material considerably improves the power conversion efficiency of the cells, resulting in a 45% increase in short-circuit current density ( JSC). This study uses capsician as a bonding agent to enhance the current density of a graphene–TiO2 based semi-organic solar cell. The mechanical and electrical properties of the cell are investigated using a scanning electron microscope, energy dispersive X-ray, and Corescan.

Fabrication and characterization of methylammonium lead iodide-based perovskite solar cells under ambient conditions

<p>This study investigated the fabrication and characterization of CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> based perovskite solar cells (PSCs) using the one-step spin coating technique under ambient conditions, eliminating the need for expensive glovebox and thermal evaporation equipment. The perovskite layer was annealed at 65 °C for 30 seconds and 100 °C for 30 seconds, 1 and 2 minutes. The scanning electron microscope (SEM) images show a smooth and uniform surface coverage for the ETL and CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> layers. SEM results also show an average grain size of 397 nm for CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> and an average particle size of ~17 nm for TiO<sub>2</sub> was confirmed by transmission electron microscopy (TEM). X-ray diffraction (XRD) results confirmed the formation of tetragonal perovskite (CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub>) phase with high crystallinity with a crystallite size of 19.99 nm for the samples annealed for 30 seconds at 65 °C and 1 min at 100 °C. FTIR results also confirmed the presence of anatase TiO2 at wavenumber 438 cm<sup>-1</sup> and the formation of the adduct of Pb<sub>2</sub> with dimethyl sulfoxide (DMSO) and MAI is confirmed at 1,015 cm<sup>-1</sup> . From the Tauc plot the bandgap energy of TiO2 and Perovskite layers was determined to be 3.52 eV and 2.06 eV respectively. An open-circuit voltage was 0.9057 V and short circuit current density was 12.2185 mA/cm<sup>2</sup> with a fill factor of 48.05 and power conversion efficiency (PCE) of 5.199%.</p>

Interface Passivation of a Pyridine-Based Bifunctional Molecule for Inverted Perovskite Solar Cells.

Organic-inorganic hybrid perovskite solar cells (PSCs) have recently been demonstrated to be promising renewable harvesters because of their prominent photovoltaic power conversion efficiency (PCE), although their stability and efficiency still have not reached commercial criteria. Trouble-oriented analyses showcase that defect reduction among the grain boundaries and interfaces in the prepared perovskite polycrystalline films is a practical strategy, which has prompted researchers to develop functional molecules for interface passivation. Herein, the pyridine-based bifunctional molecule dimethylpyridine-3,5-dicarboxylate (DPDC) was employed as the interface between the electron-transport layer and perovskite layer, which achieved a champion PCE of 21.37% for an inverted MAPbI3-based PSC, which was greater than 18.64% for the control device. The mechanistic studies indicated that the significantly improved performance was mainly attributed to the remarkably enhanced fill factor with a value greater than 83%, which was primarily due to the nonradiative recombination suppression offered by the passivation effect of DPDC. Moreover, the promoted carrier mobility together with the enlarged crystal size contributed to a higher short-circuit current density. In addition, an increase in the open-circuit voltage was also observed in the DPDC-treated PSC, which benefited from the improved work function for reducing the energy loss during carrier transport. Furthermore, the DPDC-treated PSC showed substantially enhanced stability, with an over 80% retention rate of its initial PCE value over 300 h even at a 60% relative humidity level, which was attributed to the hydrophobic nature of the DPDC molecule and effective defect passivation. This work is expected not only to serve as an effective strategy for using a pyridine-based bifunctional molecule to passivate perovskite interfaces to enhance photovoltaic performance but also to shed light on the interface passivation mechanism.

Exploring the Bi Layer Approach to Analyzing Lead-Free Perovskite Solar Cells' Numerical Aspects for High Efficiency

In the past decades the metal halide perovskites gained tremendous attention from researchers because of its excellent visible light absorption and promising power conversion efficiencies. But due its toxic nature and concerned ecological hazards it can’t be commercialized on a large scale. So there was a need to introduce a new toxic free alternative. According to this paper a volume lead free perovskite structure is quantitative investigated using SCAPS (1−D) software. A new approach is used in which The lead-free active layer CH3NH3SnI3 is encased in two bilayers of a simultaneous simulation that investigates the hole transport layer (HTL) and electron transport layer (ETL) and fine-tunes their respective thicknesses as well as the absorber layer to attain the best possible performance for the suggested structure. Furthermore, a number of parameters influencing electrical properties were studied statistically, including the effect of different rear connections, temperature changes, doping concentration in the absorber layer, defect states at interfaces, and the overall density of defects. The optimal configuration yielded an open circuit voltage (Voc) of 0.96V, a short circuit current density (Jsc) of 32mA/cm2, a Fill Factor of 82.02, and a power conversion efficiency of 26.09% under standard AM1.5 G conditions.

Improving the Efficiency and Stability of Perovskite Solar Cells by Refining the Perovskite-Electron Transport Layer Interface and Shielding the Absorber from UV Effects.

This study aims to enhance the performance of perovskite solar cells (PSCs) by optimizing the interface between the perovskite and electron transport layers (ETLs). Additionally, we plan to protect the absorber layer from ultraviolet (UV) degradation using a ternary oxide system comprising SnO2, strontium stannate (SrSnO3), and strontium oxide (SrO). In this structure, the SnO2 layer functions as an electron transport layer, SrSnO3 acts as a layer for UV filtration, and SrO is employed to passivate the interface. SrSnO3 is characterized by its chemical stability, electrical conductivity, extensive wide band gap energy, and efficient absorption of UV radiation, all of which significantly enhance the photostability of PSCs against UV radiation. Furthermore, incorporating SrSnO3 into the ETL improves its electronic properties, potentially raising the energy level and improving alignment, thereby enhancing the electron transfer from the perovskite layer to the external circuit. Integrating SrO at the interface between the ETL and perovskite layer reduces interface defects, thereby reducing charge recombination and improving electron transfer. This improvement results in higher solar cell efficiency, reduced hysteresis, and extended device longevity. The benefits of this method are evident in the observed improvements: a noticeable increase in open-circuit voltage (Voc) from 1.12 to 1.16 V, an enhancement in the fill factor from 79.4 to 82.66%, a rise in the short-circuit current density (Jsc) from 24.5 to 24.9 mA/cm2 and notably, a marked improvement in the power conversion efficiency (PCE) of PSCs, from 21.79 to 24.06%. Notably, the treated PSCs showed only a slight decline in PCE, reducing from 24.15 to 22.50% over nearly 2000 h. In contrast, untreated SnO2 perovskite devices experienced a greater decline, with efficiency decreasing from 21.79 to 17.83% in just 580 h.

Simulation and optimization of 30.17% high performance N-type TCO-free inverted perovskite solar cell using inorganic transport materials

Perovskite solar cells (PSCs) have gained much attention in recent years because of their improved energy conversion efficiency, simple fabrication process, low processing temperature, flexibility, light weight, and low cost of constituent materials when compared with their counterpart silicon based solar cells. Besides, stability and toxicity of PSCs and low power conversion efficiency have been an obstacle towards commercialization of PSCs which has attracted intense research attention. In this research paper, a Glass/Cu2O/CH3NH3SnI3/ZnO/Al inverted device structure which is made of cheap inorganic materials, n-type transparent conducting oxide (TCO)-free, stable, photoexcited toxic-free perovskite have been carefully designed, simulated and optimized using a one-dimensional solar cell capacitance simulator (SCAPS-1D) software. The effects of layers’ thickness, perovskite’s doping concentration and back contact electrodes have been investigated, and the optimized structure produced an open circuit voltage (Voc) of 1.0867 V, short circuit current density (JSC) of 33.4942 mA/cm2, fill factor (FF) of 82.88% and power conversion efficiency (PCE) of 30.17%. This paper presents a model that is first of its kind where the highest PCE performance and eco-friendly n-type TCO-free inverted CH3NH3SnI3 based perovskite solar cell is achieved using all-inorganic transport materials.

Eco-friendly solvent-processed layer-by-layer ternary all-polymer solar cells exhibiting over 18.5% efficiency

In this work, a series of eco-friendly solvent-processed all-polymer solar cells (APSCs) were fabricated by employing the sequentially spin-coating method. Two polymer donor materials PBQx-TCl and PM6 were deliberately selected due to their similar chemical structure, preferring to form the alloyed state for better exciton dissociation and hole transport in the layer-by-layer (LbL) APSCs. The better exciton dissociation between PBQx-TCl and PM6 can be confirmed from PL spectra of neat and blend films, as well as the short-circuit current densities (JSC) of special cells without acceptor layer. The optimized ternary LbL APSCs with 30 wt% PM6 in donor layer exhibit the power conversion efficiency (PCE) of 18.55 %, originating from the simultaneously improved JSC of 25.16 mA cm−2, open-circuit voltage (VOC) of 0.966 V, and fill factor of 76.33 %. The increased VOC of ternary LbL APSCs is mainly attributed to the decreased energy loss due to the good compatibility of the two polymer donors. The PCE of 18.55 % should be among the highest value for LbL APSCs processed by eco-friendly solvent.

Simultaneous enhancement of photocurrent and open circuit voltage in ternary organic solar cells by red fluorescent material as third component materials

Ternary organic solar cells (OSCs) were constructed using D18-Cl:Y6 as the host photoactive layer and the red fluorescent material [4-(dicyano-methylene)-2-methyl-6-(p-dimethyl aminostyryl)-4H-pyran] (DCM) as the third component material. The optimized ternary OSCs (optimized weight ratio of D18-Cl:Y6:DCM is 1:1.4:0.1) showed a power conversion efficiency (PCE) of 17.36 %, a short-circuit current density (JSC) of 26.79 mA cm−2, an open-circuit voltage (VOC) of 0.89 V, and a fill factor (FF) of 72.8 %. Since the absorption peak of DCM is located in the red light region and the photoluminescence peak of DCM is covered by the absorption peak of D18-Cl, DCM significantly improves the short-wavelength light absorption of the optimized ternary photoactive layer and facilitates the energy transfer from DCM to D18-Cl. While increasing the DCM content, the LUMO level of the blend acceptor is shifted upwards, which favors the VOC value. However, excessive amount of DCM would damage the phase separation, bulk and surface morphology of the ternary film. The results showed that the red fluorescent material DCM has great potential as a third component material for realizing highly efficient ternary OSCs.

Enhancement of photoresponse and photovoltaic properties in KBiFe2O5/BiFeO3 bilayer thin films

In this report, the performance of a new photovoltaic device configuration in which bilayer KBiFe2O5 (KBFO)/BiFeO3 (BFO) as absorber materials have been investigated and compared with the single active layer-based devices of BFO and KBFO. The obtained short-circuit current density of 58.81 μAcm−2, open-circuit voltage of 0.65 V, and power conversion efficiency of 0.014 % for the complete photovoltaic device glass/FTO/KBFO/BFO/Ag are comparatively higher than that of glass/FTO/BFO/Ag and glass/FTO/KBFO/Ag devices. It has been observed that the active bilayer KBFO/BFO shows switchable photoresponse with respect to positive and negative polarities. This work may offer the procedures for further optimizing the photo absorber layer, thereby improving the performances of multiferroic-based devices for ferroelectric photovoltaic applications.

Improved charge kinetics of BiVO4/MoS2 photoanode by an TiO2 electron transport layer for photocatalytic fuel cell photodegradation and electricity generation

The poor contact between the photocatalyst and the FTO substrate are the main factors lead to the low performance of photocatalytic fuel cell (PFC). Herein, a FTO pre-treated with a TiO2 electron transport layer was used as a substrate for the synthesis of the MoS2/BiVO4/pre-FTO photoanode. The proposed MBV-4/pre-FTO photoanode with its enhances the visible light absorption and effectively delays the recombination of the photoexcited charge. The MBV-4/pre-FTO composite photoanode (6.02 mA/cm2) exhibited a photocurrent density that was 2.2 times higher than that of the BiVO4 photoanode (2.78 mA/cm2). This is attributed to the short charge migration length of the thin MoS2 layer, the fast photoexcited electron transport effect of the TiO2 seed layer, and the heterojunction structure of the proposed photoanode. The DFT calculation result indicated that the TiO2 electron transport layer showed an outstanding photoelectron attractive and transporting effect. The MoS2/Ni foam was employed as the photocathode to establish a mismatched Fermi level for driving PFC. The short-circuit current, open-circuit voltage, and maximum power density of the PFC were 0.578 mA/cm2, 0.632 V, and 0.125 mW/cm2, respectively. The main photodegradation active species are the superoxide anion (∙O2–) and the photoexcited hole (h+), and the degradation efficiency is 61.97 %.

Simulation research of hole transport layer free CsPbI3/MAPbI3 heterojunction perovskite solar cells with an efficiency of 30.33 %

Constructing inorganic perovskite/organic-inorganic hybrid perovskite bilayer heterojunction perovskite solar cells (HPSC) could make far-reaching changes in solar cell power conversion efficiency (PCE). Herein, a carbon-based hole transport layer (HTL) free CsPbI3/MAPbI3 HPSC was designed and optimized by one-dimensional solar cell capacitance (SCAPS-1D) software. The film thickness, bulk defect density and doping concentration of each perovskite light absorption layer, and the interface defect density, the electrode work function and the operating temperature changes effect on the device performances were investigated. Under optimized conditions, the HPSC obtained the open circuit voltage (VOC) of 1.43 V, short circuit current density (JSC) of 23.39 mA cm−2, fill factor (FF) of 90.67 % and PCE of 30.33 %, which was much superior than the single junction perovskite solar cell due to the suited energy band structure.

Exploring the potential of green synthesized ZnO-SnO2 composite as an effective electron transport layer for perovskite solar cells: A sustainable approach

Utilizing green-synthesized ZnO nanoparticles as an electron transport layer (ETL) is a key strategy in perovskite solar cell applications, leveraging their high electron mobility, conductivity, stability against photo-corrosion, and cost-effectiveness. In this study, these environmentally synthesized nanoparticles, combined with SnO2, formed a composite solution-processed ETL achieving an impressive 18.09 % device efficiency, with 1.06 V open circuit voltage, 71.71 % fill factor, and 23.80 mA/cm2 short circuit current density. These values underscore the composite material's potential for device applications. Additionally, capacitance measurements investigated ETL and absorber layer interfaces, yielding crucial insights into their behaviour under varying voltage, frequency, and illumination conditions. The study highlights the ZnO-NP and SnO2 composite's efficacy as a superior ETL in PSCs, emphasizing the environmental sustainability implications of employing green-synthesized materials in solar energy technologies.

Buried Interface Passivation Using Organic Ammonium Salts for Efficient Inverted CsMAFA Perovskite Solar Cell Performance.

This study uses different doping ratios of CsCl and MACl dual additives to improve the quality of the perovskite, where CsCl reduces the perovskite trap density and increases the resistance of charge recombination, and MACl was used to improve the phase stability. Finally, the composition of Cs0.1MA0.09FA0.81PbCl0.14I2.86 perovskite solar cell (PeSC) can achieve better open-circuit voltage (Voc), short-circuit current density (Jsc), and photoelectric conversion efficiency (PCE). To achieve a better PCE of PeSC, the use of organic ammonium salt butane-1,4-diammonium iodide (BDAI2) to passivate the perovskite bottom surface (buried interface) can effectively suppress the formation of defects at the perovskite buried interface, obtain higher crystallinity, and thereby reduce the probability of carrier recombination. The Jsc, fill factor (FF), and PCE of the PeSC based on BDAI2 passivation increased from 24.0 mA cm-2, 74.1%, and 18.6% to 24.5 mA cm-2, 79.9%, and 20.5%, respectively.

Se Inter-Diffusion Limits Absorber Layer Grain Growth in CdSe - CdTe Photovoltaics

Diffusion of Se from the CdSe window layer into the CdTe absorber improves the short circuit current density by narrowing the band gap and increasing the carrier lifetime. Thicker CdSe layers, however, show a dramatic loss in photocurrent collection due to Se over-alloying. Electron microscopy investigations show that this decrease in performance is due to the formation of small grains (∼783 nm average diameter), which exhibit grain boundary porosity in the Se inter-diffusion region. The larger grain boundary area and void free surfaces give rise to higher levels of nonradiative recombination, and therefore, a lower photocurrent. It is proposed that the small grain size is due to a drag force exerted by segregated Se solute atoms on a moving grain boundary, while faster Se diffusion along the grain boundaries results in vacancy build up and porosity due to the Kirkendall effect. The results indicate that the device processing conditions must be carefully controlled such that the negative effects of Se alloying (i.e., smaller grains, Kirkendall voids) do not undermine its benefits. Published by the American Physical Society 2024

Improved performance of ternary organic solar cells based on both bulk and pseudo-planar heterojunction active layer

The high photovoltaic conversion efficiency (PCE) of ternary organic solar cells (OSCs) based on PTB7-Th, PC71BM and IEICO-4F material is obtained, the short-circuit current density (J SC), fill factor (FF), and open-circuit voltage is 25.90 mA cm−2, 73.20% and 0.71 V, respectively. PCE is as high as 13.53%. It is the highest PCE of ternary OSCs based on PTB7-Th, PC71BM and IEICO-4F materials for all we know. The narrow bandgap material of IEICO-4F is deposited on PTB7-Th:PC71BM bulk heterojunction (BHJ) by layer-by-layer process. We constructed the dual bandgap active layer both BHJ and pseudo-planar heterojunction (P-PHJ), it could be defined as ternary BHJ/P-PHJ of OSCs. This type of OSCs is not only the complementary bandgap material of the active layer, but also increasing the donor/acceptor (D/A) interface. The excitons generation and collection of the device are increased leading a higher J SC and FF. The semitransparent OSCs (ST-OSCs) is prepared by varying the thickness of Ag electrode and PCE can reach 9.70%, and the average visible light transmittance and light use efficiency of ST-OSCs are improved effectively.

Perovskite Colloidal Nanocrystal Solar Cells: Current Advances, Challenges, and Future Perspectives.

The power conversion efficiencies (PCEs) of polycrystalline perovskite (PVK) solar cells (SCs) (PC-PeSCs) have rapidly increased. However, PC-PeSCs are intrinsically unstable without encapsulation, and their efficiency drops during large-scale production; these problems hinder the commercial viability of PeSCs. Stability can be increased by using colloidal PVK nanocrystals (c-PeNCs), which have high surface strains, low defect density, and exceptional crystal quality. The use of c-PeNCs separates the crystallization process from the film formation process, which is preponderant in large-scale fabrication. Consequently, the use of c-PeNCs has substantial potential to overcome challenges encountered when fabricating PC-PeSCs. Research on colloidal nanocrystal-based PVK SCs (NC-PeSCs) has increased their PCEs to a level greater than those of other quantum-dot SCs, but has not reached the PCEs of PC-PeSCs; this inferiority significantly impedes widespread application of NC-PeSCs. This review first introduces the distinctive properties of c-PeNCs, then the strategies that have been used to achieve high-efficiency NC-PeSCs. Then it discusses in detail the persisting challenges in this domain. Specifically, the major challenges and solutions for NC-PeSCs related to low short-circuit current density Jsc are covered. Last, the article presents a perspective on future research directions and potential applications in the realm of NC-PeSCs.

Impact of La doping on the optoelectronic and structural properties of CsPbIBr2 perovskite solar cell

Inorganic lead halide perovskite solar cells (IPSC) have high power conversion efficiency (PCE). Currently, heteroatom substitution is a promising method for enhancing the properties of perovskite materials and the performance of associated devices. This study outlines the production process of a perovskite solar cell made from inorganic CsPbIBr2 with a 4 % La doping. The cubic crystal structure with large grain size and small band gap energy is observed at 4 % La–CsPbIBr2. The optoelectronic and structural characteristics of CsPbIBr2 perovskite solar cells have been substantiated through various methodologies, such as the determination of space charge restricted current, examination of the photoluminescence decay profile, assessment of charge transfer resistance, and utilization of Mott Schottky analysis. The incorporation of lanthanum-doped cesium lead iodide bromide (La-doped CsPbIBr2) resulted in a notable enhancement in both the open circuit voltage (Voc), and the short circuit current density (Jsc), leading to a much higher overall efficiency of 9.89 % compared to the pristine counterpart, which exhibited an efficiency of 8.62 %.

Acceptor molecules with Carbon–Carbon singly bonded central and terminal units for efficient P3HT-based organic solar cells

Herein, we synthesized two small molecules named as 4TBTCN and 6TBTCN with strongly electron-rich 4,4,9,9-tetrakis(4-hexylphenyl)-4,9-dihydrothieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene or 6,6,12,12-tetrakis(4-hexylphenyl)-6,12-dihydrothieno[2″,3′′:4′,5′]thieno[3′,2′:4,5]cyclopenta[1,2-b]thieno[2‴,3‴:4″,5′′]thieno[2″,3′′:3′,4′]cyclopenta[1′,2′:4,5]thieno[2,3-d]thiophene as central unit and weak electron-withdrawing benzo[c] [1,2,5] thiadiazole-4-carbonitrile as termini, which were connected by C–C single bond. Both molecules exhibited medium optical bandgap and high-lying frontier molecular orbital energy levels, which were matched with those of the representative low-cost polymer donor P3HT. Moreover, 4TBTCN and 6TBTCN showed high stability under continuous illumination and base condition, owing to a lack of exocyclic vinyl group between the central unit and end group. Compared to P3HT:6TBTCN, P3HT:4TBTCN blend system displayed lower miscibility and thus more distinct phase separation, leading to more efficient charge transport and collection. Although the LUMO energy level of 4TBTCN was 0.15 eV deeper than that of 6TBTCN, the energy loss for P3HT:4TBTCN based device was similar to that of P3HT:6TBTCN based device. As a result, P3HT:4TBTCN based device displayed a similar open-circuit voltage but higher fill factor and short-circuit current density, yielding a superior power conversion efficiency, in comparison to P3HT:6TBTCN based device. This work provides a new strategy for design of efficient and stable acceptor molecules.