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Creators/Authors contains: "Dai, Zhenghong"

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  1. Free, publicly-accessible full text available May 1, 2024
  2. Abstract

    The combined effects of compact TiO2(c‐TiO2) electron‐transport layer (ETL) are investigated without and with mesoscopic TiO2(m‐TiO2) on top, and without and with an iodine‐terminated silane self‐assembled monolayer (SAM), on the mechanical behavior, opto–electronic properties, photovoltaic (PV) performance, and operational‐stability of solar cells based on metal‐halide perovskites (MHPs). The interfacial toughness increases almost threefold in going from c‐TiO2without SAM to m‐TiO2with SAM. This is attributed to the synergistic effect of the m‐TiO2/MHP nanocomposite at the interface and the enhanced adhesion afforded by the iodine‐terminated silane SAM. The combination of m‐TiO2and SAM also offers a significant beneficial effect on the photocarriers extraction at the ETL/MHP interface, resulting in perovskite solar cells (PSCs) with power‐conversion efficiency (PCE) of over 24% and 20% for 0.1 and 1 cm2active areas, respectively. These PSCs also have exceptionally long operational‐stability lives: extrapolatedT80 (duration at 80% initial PCE retained) is ≈18 000 and 10 000 h for 0.1 and 1 cm2active areas, respectively.Postmortemcharacterization and analyses of the operational‐stability‐tested PSCs are performed to elucidate the possible mechanisms responsible for the long operational‐stability.

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  3. Abstract

    Two key interfaces in flexible perovskite solar cells (f‐PSCs) are mechanically reinforced simultaneously: one between the electron‐transport layer (ETL) and the 3D metal‐halide perovskite (MHP) thin film using self‐assembled monolayer (SAM), and the other between the 3D‐MHP thin film and the hole‐transport layer (HTL) using an in situ grown low‐dimensional (LD) MHP capping layer. The interfacial mechanical properties are measured and modeled. This rational interface engineering results in the enhancement of not only the mechanical properties of both interfaces but also their optoelectronic properties holistically. As a result, the new class of dual‐interface‐reinforced f‐PSCs has an unprecedented combination of the following three important performance parameters: high power‐conversion efficiency (PCE) of 21.03% (with reduced hysteresis), improved operational stability of 1000 hT90(duration at 90% initial PCE retained), and enhanced mechanical reliability of 10 000 cyclesn88(number of bending cycles at 88% initial PCE retained). The scientific underpinnings of these synergistic enhancements are elucidated.

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  4. Iodine-terminated self-assembled monolayer (I-SAM) was used in perovskite solar cells (PSCs) to achieve a 50% increase of adhesion toughness at the interface between the electron transport layer (ETL) and the halide perovskite thin film to enhance mechanical reliability. Treatment with I-SAM also increased the power conversion efficiency from 20.2% to 21.4%, reduced hysteresis, and improved operational stability with a projected T80 (time to 80% initial efficiency retained) increasing from ~700 hours to 4000 hours under 1-sun illumination and with continuous maximum power point tracking. Operational stability–tested PSC without SAMs revealed extensive irreversible morphological degradation at the ETL/perovskite interface, including voids formation and delamination, whereas PSCs with I-SAM exhibited minimal damage accumulation. This difference was attributed to a combination of a decrease in hydroxyl groups at the interface and the higher interfacial toughness.

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