D-A-π-A-D-type Dopant-free Hole Transport Material for Low-Cost, Efficient, and Stable Perovskite Solar Cells

Developing low‐cost, efficient, and stable dopant‐free hole‐transporting materials (HTMs) in perovskite solar cells (PVSCs) is essential to their commercial deployment. Herein, the synthesis of a novel spirofluorene‐dithiolane based small molecular HTM, SFDT‐TDM, through facile and low‐cost synthetic routes is reported. The CH…π interactions in adjacent SFDT‐TDM are beneficial for high hole mobility and the methylthio groups in SFDT‐TDM can serve as Lewis bases to passivate the defects on the surface of perovskite films, leading to suppressed non‐radiative recombination and enhanced charge extraction at the perovskite/HTM interface. As a result, CsxFA1−xPbI3 based PVSCs with SFDT‐TDM as the HTM realize champion power conversion efficiencies (PCEs) of 21.7% and 20.3% for small‐area (0.04 cm2) and large‐area (1.0 cm2) devices with negligible photocurrent hysteresis, respectively. Additionally, all‐inorganic CsPbI3−xBrx based PVSCs with SFDT‐TDM demonstrate an impressive PCE of 17.1% along with excellent stability. This work highlights the great potential of the spirofluorene core for exploring low‐cost and dopant‐free HTMs for PVSCs with high efficiency and stability.

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“…The lower n value suggests the SFDT‐TDM can reduce the defect‐induced Shockley–Read–Hall recombination more efficiently. [ 16 ]…”

Section: Resultsmentioning

confidence: 99%

Dopant‐Free Hole‐Transporting Material with Enhanced Intermolecular Interaction for Efficient and Stable n‐i‐p Perovskite Solar Cells

Wang

Liu

et al. 2021

Advanced Energy Materials

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“…It is worth noting that we chose spiro-OMeTAD as reference because of its wide use, however other HTMs enabled reaching high efficiency, sometimes even without the use of dopants. [45][46][47][48][49][50] We believe our own concept of halo-functional HTM could be further developed to achieve even higher efficiencies, ideally without the need of doping. Therefore, with this work we wish to show the advantages of this kind of HTM and we hope to pave the way to a new set of halo-functional materials leading to high efficiency and stable devices.…”

Section: Resultsmentioning

confidence: 99%

Halogen‐Bonded Hole‐Transport Material Suppresses Charge Recombination and Enhances Stability of Perovskite Solar Cells

Canil

Salunke

Wang

et al. 2021

Advanced Energy Materials

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Interfaces play a crucial role in determining perovskite solar cells, (PSCs) performance and stability. It is therefore of great importance to constantly work toward improving their design. This study shows the advantages of using a hole‐transport material (HTM) that can anchor to the perovskite surface through halogen bonding (XB). A halo‐functional HTM (PFI) is compared to a reference HTM (PF), identical in optoelectronic properties and chemical structure but lacking the ability to form XB. The interaction between PFI and perovskite is supported by simulations and experiments. XB allows the HTM to create an ordered and homogenous layer on the perovskite surface, thus improving the perovskite/HTM interface and its energy level alignment. Thanks to the compact and ordered interface, PFI displays increased resistance to solvent exposure compared to its not‐interacting counterpart. Moreover, PFI devices show suppressed nonradiative recombination and reduced hysteresis, with a Voc enhancement of ≥20 mV and a remarkable stability, retaining more than 90% efficiency after 550 h of continuous maximum‐power‐point tracking. This work highlights the potential that XB can bring to the context of PSCs, paving the way for a new halo‐functional design strategy for charge‐transport layers, which tackles the challenges of charge transport and interface improvement simultaneously.

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“…The lower HOMO of CI‐TTIN‐2F is expected to ensure more efficient interfacial hole‐transport kinetics and improve the open‐circuit voltage ( V OC ) for CsPbI 3 PSCs. [21] …”

Section: Resultsmentioning

confidence: 99%

Dopant‐Free Hole Transport Materials Afford Efficient and Stable Inorganic Perovskite Solar Cells and Modules

et al. 2021

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The emerging CsPbI3 perovskites are highly efficient and thermally stable materials for wide‐band gap perovskite solar cells (PSCs), but the doped hole transport materials (HTMs) accelerate the undesirable phase transition of CsPbI3 in ambient. Herein, a dopant‐free D‐π‐A type HTM named CI‐TTIN‐2F has been developed which overcomes this problem. The suitable optoelectronic properties and energy‐level alignment endow CI‐TTIN‐2F with excellent charge collection properties. Moreover, CI‐TTIN‐2F provides multisite defect‐healing effects on the defective sites of CsPbI3 surface. Inorganic CsPbI3 PSCs with CI‐TTIN‐2F HTM feature high efficiencies up to 15.9 %, along with 86 % efficiency retention after 1000 h under ambient conditions. Inorganic perovskite solar modules were also fabricated that exhibiting an efficiency of 11.0 % with a record area of 27 cm2. This work confirms that using efficient dopant‐free HTMs is an attractive strategy to stabilize inorganic PSCs for their future scale‐up.

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D-A-π-A-D-type Dopant-free Hole Transport Material for Low-Cost, Efficient, and Stable Perovskite Solar Cells

Cited by 257 publications

References 76 publications

Dopant‐Free Hole‐Transporting Material with Enhanced Intermolecular Interaction for Efficient and Stable n‐i‐p Perovskite Solar Cells

Dopant‐Free Hole‐Transporting Material with Enhanced Intermolecular Interaction for Efficient and Stable n‐i‐p Perovskite Solar Cells

Halogen‐Bonded Hole‐Transport Material Suppresses Charge Recombination and Enhances Stability of Perovskite Solar Cells

Dopant‐Free Hole Transport Materials Afford Efficient and Stable Inorganic Perovskite Solar Cells and Modules

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