Grain boundaries in lead halide perovskite films lead to increased recombination losses and decreased device stability under illumination due to defect‐mediated ion migration. The effect of a conjugated polymer additive, poly(bithiophene imide) (PBTI), is investigated in the antisolvent treatment step in the perovskite film deposition by comprehensive characterization of perovskite film properties and the performance of inverted planar perovskite solar cells (PSCs). PBTI is found to be incorporated within grain boundaries, which results in an improvement in perovskite film crystallinity and reduced defects. The successful defect passivation by PBTI yields reduces recombination losses and consequently increases power conversion efficiency (PCE). In addition, it gives rise to improved photoluminescence stability and improved PSC stability under illumination which can be attributed to reduced ion migration. The optimal devices exhibit a PCE of 20.67% compared to 18.89% of control devices without PBTI, while they retain over 70% of the initial efficiency after 600 h under 1 sun illumination compared to 56% for the control devices.

As a new type of quasi-two-dimensional nanomaterial, CdSe nanoplatelets (NPLs) possess excellent properties such as narrow emission peak, large absorption cross section, and a low threshold of amplified spontaneous emission. However, the origin of emission especially at low temperatures has not been studied clearly up till now. Here, we study the temperature-dependent photoluminescence of CdSe NPLs which show two emission peaks at low temperatures. It is interesting to note that the intensity of the low-energy peak shows a correlation with laser irradiation time. Moreover, the low-temperature PL spectra of four CdSe NPLs with different lateral sizes demonstrate the relationship of low-energy peaks with the surface. It has been confirmed that CdSe NPLs with larger surface areas to volume ratio have stronger low-energy emissions, which is ascribed to the surface-state-related emission. Finally, surface passivation of CdSe NPLs attenuates the intensity of the low-energy peak, which further verifies our model. Our results demonstrate the critical significance of surface in CdSe NPLs for their optical properties, which is crucial for the application of optoelectronic devices.

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We demonstrate a substantial suppression of interfacial trap states in inverted PSCs via CdZnSeS QDs, leading to a large efficiency improvement.

Water-soluble CdSe/CdS nanocrystals stabilized using cysteine molecules exhibit efficient circular dichroism and large multiphoton absorption and show applications in two-photon fluorescence lifetime imaging and photodynamic therapy.

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Quasi-two-dimensional(2D) perovskites are promising candidates for light generation owing to their high radiative rates.H owever,s trong exciton-phonon interactions caused by mechanical softening of the surface act as ab ottleneck in improving their suitability for awide range of lighting and displayapplications.Moreover,itisnot easily available to tune the phonon interactions in bulk films.H ere,w ea dopt bottom-up fabricated blue emissive perovskite nanoplatelets (NPLs) as model systems to elucidate and as well as tune the phonon interactions via engineering of binary NPL solids.By optimizing component domains,the phonon coupling strength can be reduced by afactor of 2driven by the delocalization of 2D excitons in out-of-plane orientations.I ts hows the picosecond energy transfer originated from the Fçrster resonance energy transfer (FRET) efficiently competes with the excitonphonon interactions in the binary system.

Strain compensation in a Zn doped MAPbBr3 single crystal under light illumination gives rise to improved photostability in terms of temperature and time to the benefit of photodetector.