Circular polarized luminescence (CPL) is essential to chiral sciences and photonic technologies, but the achievement of circular polarized room-temperature phosphorescence (CPRTP) remains a great challenge due to the instability of triplet state excitons. Herein, we found that dual CPL and CPRTP were demonstrated by hybrid chiral photonic films designed by the coassembly of cellulose nanocrystals (CNCs), poly(vinyl alcohol) (PVA), and carbon dots (CDs). Tunable photonic band gaps were achieved by regulating the ratio of CNC/PVA in the hybrid films, leading to tunable CPL with invertible handedness, tunable wavelengths, and considerable dissymmetric factors (g lum ) up to −0.27. In particularly, triplet excitons produced by CDs were stable in the chiral photonic crystal environment, resulting in tunable right-handed CPRTP with long lifetimes up to 103 ms and large RTP dissymmetric factors (g RTP ) up to −0.47. Moreover, patterned films with multiple polarized features were demonstrated by a mold technique.
Exploring semiconductor quantum dots (QDs) with circularly polarized luminescence (CPL) is desirable to design optoelectronic devices owing to the easily tunable emission wavelengths and photophysical stability.
The development of quasi-two-dimensional (2D) Ruddlesden-Popper phase perovskite solar cells (PSCs) has greatly improved the stability of devices. However, the presence of quantum confinement effects and insulating spacer cations in...
Mixed-halide perovskite has an irreplaceable role as wide-bandgap absorber in multi-junction tandem solar cells. However, large open-circuit voltage (V oc ) loss due to non-uniform halide distribution and compromised device stability due to photo-induced halide segregation has significantly limited the applications. Here, it is introduced 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride (ABF) with multifunctional groups (sulfonyl, ammonium, and fluoride) to the mixed-halide precursor to demonstrate a downward homogenized crystallization strategy for suppressing the initial vertical halide phase separation during perovskite crystallization and reducing V oc loss. Furthermore, fluoride with strong electronegativity effectively fixes anions and cations, while sulfonyl and ammonium are used to passivate positive charged (halide vacancies) and negative charged (FA/MA vacancies) defects, respectively, thereby reducing the generation of ion vacancies that lead to subsequent photo-induced halide segregation. As a result, the 1.63 and 1.68 eV wide-bandgap perovskite solar cells with inverted structures exhibit the champion power conversion efficiency (PCE) of 21.76% and 20.11% with V oc of 1.18 and 1.21 V, respectively. Most importantly, the optimized devices without encapsulation preserve 86% of initial efficiency after 240 h of continuous illumination under AM 1.5G, showing excellent light stability. Thus, the homogenized crystallization strategy provides highly efficient performance and stability for future tandem solar cell applications.
In the journey to obtain well-crystallized mixed tin (Sn) -lead (Pb) iodide perovskite films for solar cell application, great difficulties have been presented due to very different crystallization rates between...
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