Search

Suppressing the interfacial energy losses of the buried hole-selective layer (HSL) is essential to upgrade the power conversion efficiencies (PCEs) of inverted perovskite solar cells (PSCs). In this regard, innovations in hole-extraction materials featuring self-assembled molecule (SAM) characteristics show great potential. Herein, two SAMs of C-2PACz and S-2PACz based on phenyl- and thienyl-substituted carbazole units, respectively, were developed to serve as multifunctional HSLs. The pendant phenyl and thienyl units increase the dipole moment of the SAMs as compared to that of the standard control 2PACz, which was used to efficiently modulate the work function of ITO and form desirable energy level alignments with a perovskite absorber. C-2PACz and S-2PACz SAMs possess greater capability to passivate the interface defects of a perovskite absorber, especially S-2PACz, due to the electrostatic interaction between the under-coordinated Pb2+ and S of thiophene. C-2PACz and S-2PACz with increased conjugation also show higher conductivity to promote charge transport. Moreover, HSLs based on C-2PACz and S-2PACz form a template for the crystallization of the perovskite layer to achieve more dense and uniform crystalline grains and higher crystallinity. Owing to the above-mentioned synergistic effects, C-2PACz- and S-2PACz-derived solar cells exhibit low non-radiative recombination loss, higher PCEs and enhanced stability compared to the control device with 2PACz. [ABSTRACT FROM AUTHOR]

Photoactive black‐phase formamidinium lead triiodide (α‐FAPbI3) perovskite has dominated the prevailing high‐performance perovskite solar cells (PSCs), normally for those spin‐coated, conventional n‐i‐p structured devices. Unfortunately, α‐FAPbI3 has not been made full use of its advantages in inverted p‐i‐n structured PSCs fabricated via blade‐coating techniques owing to uncontrollable crystallization kinetics and complicated phase evolution of FAPbI3 perovskites during film formation. Herein, a customized crystal surface energy regulation strategy has been innovatively developed by incorporating 0.5 mol % of N‐aminoethylpiperazine hydroiodide (NAPI) additive into α‐FAPbI3 crystal‐derived perovskite ink, which enabled the formation of highly‐oriented α‐FAPbI3 films. We deciphered the phase transformation mechanisms and crystallization kinetics of blade‐coated α‐FAPbI3 perovskite films via combining a series of in‐situ characterizations and theoretical calculations. Interestingly, the strong chemical interactions between the NAPI and inorganic Pb−I framework help to reduce the surface energy of (100) crystal plane by 42 %, retard the crystallization rate and lower the formation energy of α‐FAPbI3. Benefited from multifaceted advantages of promoted charge extraction and suppressed non‐radiative recombination, the resultant blade‐coated inverted PSCs based on (100)‐oriented α‐FAPbI3 perovskite films realized promising efficiencies up to 24.16 % (~26.5 % higher than that of the randomly‐oriented counterparts), accompanied by improved operational stability. This result represented one of the best performances reported to date for FAPbI3‐based inverted PSCs fabricated via scalable deposition methods. [ABSTRACT FROM AUTHOR]

Bubble detection in water plays important roles in human exploration and management of the ocean. This research presents a detection technique based on laser polarization dual-mode fusion, aiming at solving the difficulties of light scattering intensity characteristics that are hard to extract and the small particle size of underwater bubbles that are hard to detect. To increase the precision of bubble identification, an image fusion technique based on bubble polarization degree is first presented. Second, we quantitatively investigate the grayscale undulation of bubbles with different size and number distributions in the image from both statistical and experimental aspects, introduce image grayscale fluctuation (GF) to fuse two modes of laser polarization and the image, establish an a posteriori distribution probability model of discriminating features such as the size and number of bubbles, and realize the bubble small-sample, multi-source data fitting. The findings demonstrate that dynamic bubble detection in the 50–1000 μm and 100–2000 cm−3 ranges can achieve more than 95%, as well as more than a 93%, accuracy in quantity distribution and bubble size change. This technique achieves the continuous perception of bubble features in complicated underwater environments, and offers a possible application scheme for the detection of marine bubble environments. [ABSTRACT FROM AUTHOR]

All-polymer solar cells (all-PSCs) show great promise for use as portable and wearable electronic power sources. It is well recognized that a gradient distribution of the two components of the active layer of all-PSCs is preferred to facilitate charge transport and suppress non-radiative recombination loss. Herein, two polymers of PBS-DIT and PTPH-DIT were designed and synthesized by changing the linking mode of a benzothiophene side chain located on a benzodithiophene (BDT) skeleton, and the influences of isomerization on the blend morphology and device performance were investigated. PBS-DIT with the BDT moiety linked to the benzene ring of benzothiophene exhibited stronger solution aggregation, better tolerance to heat processing, and finer compatibility with the acceptor of N2200. Besides, PBS-DIT induced its desirable vertical phase distribution while PTPHT-DIT was uniformly distributed over the vertical direction. Benefiting from more efficient charge transfer, higher and balanced charge transport, and less recombination loss, the all-PSCs with PBS-DIT afforded a PCE of 7.76% which is much higher than 5.31% for the blend of PTPH-DIT:N2200. The results indicate that the building block of BDT linked to the benzene ring of the benzothiophene substituent is more promising than its counterpart of BDT linked to the thiophene ring of the benzothiophene substituent. Furthermore, isomerization can be a simple yet effective method to modulate the intermolecular miscibility and vertical phase distribution. [ABSTRACT FROM AUTHOR]