No abstract

No abstract

To realize commercialization of perovskie solar cell (PVSC) technology, it is essential to reduce the device costs while maintaining high power conversion efficiencies (PCEs). So far, the high cost of the most commonly used hole selective material, 2,2′,7,7′‐Tetrakis (N,N‐di‐p‐methoxyphenylamino)‐9,9′‐spirobifluorene (spiro‐OMeTAD), for high‐PCE PVSCs presents a significant obstacle for device cost reduction. In this work, the synthesis and characterization of a new spiro‐OMeTAD derivative hole selective material, 2,6,14‐tris(5′‐(N,N‐bis(4‐methoxyphenyl)aminophenol‐4‐yl)‐3,4‐ethylenedioxythiophen‐2‐yl)‐triptycene (TET) is reported. TET features a three‐dimensional structure consisting of a triptycene core and triarylamine arms linked by 3,4‐ethylenedioxythiophene, facilitating efficient hole transport. Planar PVSCs using TET hole selective layers (HSLs) achieved high fill factors of over 81% and steady‐state efficiencies of up to 18.6%, comparable with that (19.0%) of PVSC using spiro‐OMeTAD HSL. Importantly, the hereby reported efficient PVSCs can be produced with very thin TET HSLs (about 30 nm). Considering the lower laboratory synthesis and purification cost ($123 vs. $500 g−1) and thinner HSL (30 vs. 200 nm), the cost for TET on a unit area of one device is 25 times lower than that for high‐purity spiro‐OMeTAD. The device with TET HSL shows good stability under continuous illumination. Therefore, this work makes a significant step forward toward the commercialization of the emerging PVSC technology.

Plasma processing with atmospheric pressure plasma jets (APPJs) is attracting attention from both scientific and industrial fields for their capability of flexible plasma release onto targets. It is of great significance to understand the discharge characteristic and underly mechanism of the interfacial phenomenon in plasma surface interaction. In this paper, we investigate the basic surface charging on quartz dielectrics by pulsed He APPJs with double-ring electrodes. The dynamic surface charges are quantitatively acquired with a reflective electro-optic measurement platform on Pockels effect and the fast charge inversion calculation on 2D-FTA. Dynamic distributions of surface charge deposited by the plasma jet are revealed, together with the behavior of ionization waves interacting on the quartz surface. The dependence of surface charge lifetime on pulse width is investigated. Results indicate that after ionization waves reach the surface, a round positive charge cloud is formed on quartz dielectrics with a diameter of 5 ~ 10 mm, charge density of 20 ~ 60 nC/cm2 and total deposition of 40 ~ 160 nC. The plasma jet is capable of transporting more charges onto the quartz surface at a higher rate under higher voltage magnitude. Some interesting phenomena are observed that the lifetime of surface charge relies strongly on pulse widths, almost keeping unchanged during pulse duration. Also, a polarity reversal of surface charging occurs when the pulse width increases to over half-cycle, with a reduced positive charge on pulse-on and a more negative charge deposition on pulse-off. These results provide a non-intrusive tool for an in-depth insight into the basic charging dynamics of plasma surface interaction, which will be of interest to researchers in the plasma community.

No abstract