15 Sep 01:59
by Bonkee Koo,
Wooyeon Kim,
Kiwon Choi,
June Huh,
Min Jae Ko
Sustainable self-healing perovskite solar cells (PSCs) are developed through the incorporation of dendrimers with unique molecular structures and appropriately placed functional groups. Notably, even after subjecting ten harsh degradation and recovery cycles, these PSCs maintain 90% of their initial power conversion efficiency (>26%). The underlying dendrimer-driven healing mechanism is systematically investigated and clearly elucidated.
Abstract
Perovskite solar cells (PSCs) face critical challenges owing to their intrinsic instability under harsh environmental conditions. Although various strategies are explored to enhance stability, their effects remain temporary. Herein, dendrimers are designed that serve as volatile reservoirs, enabling repeated self-healing while simultaneously enhancing power conversion efficiency (PCE). PSCs containing these dendrimers achieve a PCE exceeding 26% and recover 90% of their initial PCE after ten cycles of alternating high-humidity and dry conditions. Then the self-healing mechanism is elucidated, which is facilitated by the dendrimers capturing volatile FA and interacting with PbI6 octahedra to form intermediate phases. These phenomena afford a reversible transition between perovskite and degraded perovskite phases. This approach offers a sustainable pathway toward semi-permanent PSCs by enabling continuous self-healing of perovskite materials.
15 Sep 01:20
by Lin Hu,
Jianru Wang,
Fang Wang,
Guobin Shen,
Hongxiang Li,
Wei Li,
Yingzhi Jin,
Zhen Su,
Mengzhen Du,
Jia Yao,
Zheng Yan,
Pei Cheng,
Dan Zhou,
Erjun Zhou,
Zaifang Li
Two novel PDI-based CILs, PDINN-B2F and PDINN-B3F, are developed via bay-position fluorobenzene substitution. Among them, PDINN-B3F affords optimized energy alignment and interfacial contact, enabling the non-fullerene OSCs to deliver PCE > 20%, along with excellent device stability.
Abstract
Rational molecular engineering of cathode interlayers (CILs) is critical for elevating the overall performance of organic solar cells (OSCs). Herein, two novel perylene diimide (PDI)-based CILs, PDINN-B2F and PDINN-B3F, are designed. The fluorobenzene substituents at the bay positions of the PDI core effectively suppress excessive aggregation and improve film-forming ability. Moreover, their strong electron-withdrawing nature downshifts the frontier molecular orbital energy levels, enhancing intrinsic n-type doping and enabling favorable energy alignments. The high electronegativity of fluorine also promotes robust interfacial interactions with active layer components, resulting in intimate contact and a more ordered molecular arrangement at the contact interface. These synergistic effects collectively promote efficient electron extraction, transport, and collection at the interface. Consequently, both PDINN-B2F and PDINN-B3F function as high-performance CILs across diverse binary and ternary active layer systems. Remarkably, when 2PACz is used as the hole transport layer, non-fullerene OSCs based on PDINN-B2F and PDINN-B3F achieve outstanding power conversion efficiencies (PCEs) of 19.56% and 20.36%, respectively, outperforming the PDINN-based control device (PCE = 18.49%) in the PM6:D18:L8-BO ternary system. Furthermore, the fluorinated CILs also endow the devices with excellent air and operational stability, offering a promising design strategy for high-performance OSCs.
31 Mar 17:33
by Yong Cui,
Huifeng Yao,
Jianqi Zhang,
Kaihu Xian,
Tao Zhang,
Ling Hong,
Yuming Wang,
Ye Xu,
Kangqiao Ma,
Cunbin An,
Chang He,
Zhixiang Wei,
Feng Gao,
Jianhui Hou
By finely optimizing the alkyl chains, the nonfullerene acceptor named BTP‐eC9 is synthesized and a maximum power conversion efficiency of 17.8% in organic photovoltaic cells is recorded. This work demonstrates that the optimization of alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving photovoltaic performance.
Abstract
Optimizing the molecular structures of organic photovoltaic (OPV) materials is one of the most effective methods to boost power conversion efficiencies (PCEs). For an excellent molecular system with a certain conjugated skeleton, fine tuning the alky chains is of considerable significance to fully explore its photovoltaic potential. In this work, the optimization of alkyl chains is performed on a chlorinated nonfullerene acceptor (NFA) named BTP‐4Cl‐BO (a Y6 derivative) and very impressive photovoltaic parameters in OPV cells are obtained. To get more ordered intermolecular packing, the n ‐undecyl is shortened at the edge of BTP‐eC11 to n ‐nonyl and n ‐heptyl. As a result, the NFAs of BTP‐eC9 and BTP‐eC7 are synthesized. The BTP‐eC7 shows relatively poor solubility and thus limits its application in device fabrication. Fortunately, the BTP‐eC9 possesses good solubility and, at the same time, enhanced electron transport property than BTP‐eC11. Significantly, due to the simultaneously enhanced short‐circuit current density and fill factor, the BTP‐eC9‐based single‐junction OPV cells record a maximum PCE of 17.8% and get a certified value of 17.3%. These results demonstrate that minimizing the alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving its photovoltaic performance.