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As the conversion efficiency of solar cell approaching its theoretical limits, reducing the power loss during the collection and transmission process is a promising way to improve the performance of solar cell. Cleaved edges create recombination centers, causing up to 0.8%abs (absolute efficiency) of power loss or even more for 156 × 156 mm silicon solar cell. Due to the complexity of edge passivation technique, alternative methods are desired. This article proposes a method to minimize this problem. It is found that most of the recombination current of edge comes from the recombination near the contact and the space charge region (SCR). As a result, keeping the cleaved edge a certain distance away from the contacts and SCR can improve performance effectively. On the other hand, contactless edge can reduce the recombination from the SCR without extra manufacturing difficulty. The results indicate the edge recombination loss can be reduced to less than 0.4%abs after the distance is optimized appropriately. [ABSTRACT FROM AUTHOR]

In recent decades, non‐fullerene acceptors (NFAs) are undergoing rapid development and emerging as a hot area in the field of organic solar cells. Among the high‐performance non‐fullerene acceptors, aromatic diimide‐based electron acceptors remain to be highly promising systems. This review discusses the important progress of perylene diimide (PDI)‐based polymers as non‐fullerene acceptors in all‐polymer solar cells (all‐PSCs) since 2014. The relationship between structure and property, matching aspects between donors and acceptors, and device fabrications are unveiled from a synthetic chemist perspective. [ABSTRACT FROM AUTHOR]

Abstract: Triplet materials have been employed to achieve high‐performing organic solar cells (OSCs) by extending the exciton lifetime and diffusion distances, while the triplet non‐fullerene acceptor materials have never been reported for bulk heterojunction OSCs. Herein, for the first time, three triplet molecular acceptors based on tellurophene with different degrees of ring fusing were designed and synthesized for OSCs. Significantly, these molecules have long exciton lifetime and diffusion lengths, leading to efficient power conversion efficiency (7.52 %), which is the highest value for tellurophene‐based OSCs. The influence of the extent of ring fusing on molecular geometry and OSCs performance was investigated to show the power conversion efficiencies (PCEs) continuously increased along with increasing the extent of ring fusing. [ABSTRACT FROM AUTHOR]

Poly(3‐hexylthiophene) (P3HT)‐based organic solar cells (OSCs) have attracted much attention due to their advantages of low‐cost production and matured roll‐to‐roll manufacture. However, the efficiency of P3HT‐based OSCs lag much behind the non‐P3HT ones due to their negligible absorption of long wavelengths of light over 650 nm, high‐lying highest occupied molecular orbitals (HOMO), and difficulty of controlling morphology. In this study, the alkyl chains of the nonfullerene acceptors are replaced with alkoxy chains to achieve synergistic enhancement of all three parameters ( short circuit current density (JSC), open circuit voltage (VOC), and fill factor (FF)) and thus significant increase of power conversion efficiency for P3HT‐based OSCs. As a result, the OSCs exhibit a maxima efficiency of 6.6%. The P3HT‐based systems are systematically studied with optical spectroscopy, photoluminescence, cyclic voltametry, space charge limit current, grazing incident wide‐angle X‐ray scattering, transient absorption spectroscopy, transmission electron microscope, and atomic force microscopy to probe the mechanism, which reveal that introducing alkoxy chains simultaneously increases the energy levels of the HOMO and the lowest unoccupied molecular orbitals, enhances the light absorption, improves the rigidity of the backbone and charge transport mobility, and tunes the molecular orientation and film morphology, thus improving the photovoltaic performance. This contribution provides an important guidance in the design of novel nonfullerene acceptors for high‐performance P3HT‐based OSCs. Replacement of alkyl chains with alkoxyl chains of the backbone of nonfullerene acceptors successfully increases the energy levels, enhances the light absorption, and improves charge transport mobility, which simultaneously enhances three parameters (short circuit current density (JSC), open circuit voltage (VOC), and fill factor (FF)), resulting in a highest efficiency for poly(3‐hexylthiophene) (P3HT)‐based organic solar cells (OSCs) (6.6%). [ABSTRACT FROM AUTHOR]

In order to meet the demand of large-scale production of organic solar cells and concept of green chemistry, it is essential to develop environment friendly solvent to fabricate OSCs. In this paper, we utilize thiophene (TH) and diphenyl ether (DPE) as halogen-free processing solvent to optimize performance of OSCs based on PTB7-Th:PC 71 BM, and we choose chlorobenzene (CB) and 1,8-diiodineoctane (DIO) combination as comparison. For PTB7-Th:PC 71 BM blend film based on pure TH solvent, the blend film exhibits high photoelectron conversion, efficient exciton separate and charges collection and well developed morphology properties, thus, higher V oc, J sc and FF were obtained than that of pure CB solvent. Furthermore, excellent photovoltaic performance was achieved with the addition of additive. The PCE of 9.02% from TH:5% DPE system was achieved without any thermal or solvent treatments (the pure TH processed devices PCE is 6.93%), while CB (with 2% DIO) based devices show a lower PCE of 7.41% (the pure CB processed devices PCE is 4.06%). The enhanced photovoltaic performance demonstrates that halogen-free solvent of thiophene provides a new strategy to large-scale fabrication of organic solar cells in future. Image 1 • Halogen free solvent thiophene (TH) was used to make organic solar cells based on PTB7-Th:PC 71 BM. • Compared to halogenated solvent chlorobenzene, cells made from solvent TH achieved higher performance of 6.93%. • TH (with 5% DPE) based devices achieved higher PCE of 9.02%, compared to CB (with 2% DIO) based devices with PCE of 7.41%. [ABSTRACT FROM AUTHOR]