Suchergebnisse

Metal halide perovskites having high defect tolerance, high absorption characteristics, and high carrier mobility demonstrate great promise as potential light harvesters in photovoltaics and optoelectronics and have experienced an unprecedented development since their occurrence in 2009. Semiconductor quantum dots (QDs), on the other hand, have also been proved to be very flexible toward shape, dimension, bandgap, and optical properties for constructing optoelectronic devices. Of late, a strategic combination of both materials has demonstrated extraordinary promise in photovoltaic applications and optoelectronic devices. Combining QDs and perovskites has proved to be quite an effective strategy toward the formation of pinhole-free and more stable perovskite crystals along with tunability of other properties. To boost this exciting research field, it is imperative to summarize the work done so far in recent years to provide an intriguing insight. This review is a critical account of the advanced strategy toward combining these two fascinating materials, including their different synthetic approaches regarding heteroepitaxial growth of perovskite crystals on QDs, carrier dynamics at the interface and potential application in the field of solar cells, light emitting diodes, and photodetectors. ; S.R. acknowledges Marie Skłodowska-Curie Actions (Project H2020-MSCA-IF-2019-897030). This work was supported by MCIN/AEI/ 10.13039/501100011033, JCCM (FEDER) and the European Union (EU) through projects PID2020-116519RB-I00 and SBPLY/19/180501/000212, respectively; and by the European Research Council (ERC) via Consolidator Grant (724424-No-LIMIT). P.P. acknowledges the support from National Science Centre (Poland) through project No. 2017/26/D/ST3/00910.

We describe a fast, simple and low temperature electrochemical technique for the preparation of zinc oxide layers on rigid and flexible substrates. The layers, prepared from a zinc nitrate precursor, are of high structural and optical quality. They have been optimized to be applied as efficient electron transport layers in CH3NH3PbI3-sensitized perovskite solar cells (PSCs). We show that an electrodeposition time of only two minutes and a low processing temperature are sufficient to fabricate solar cells with a power conversion efficiency close to 11%, with a high short circuit current and a small J–V curve hysteresis. The key parameters of the cell functioning have been analyzed over a large applied voltage range by the impedance spectroscopy technique. The solar cell characteristic changes with the ZnO layer deposition time are explained by the variation of the recombination and charge transfer resistances. ; J.Z. acknowledges the Guangzhou Government for scholarship (Oversea Study Program of the Guangzhou Elite Project). We thank Dr Odile Majerus for the help in Raman spectroscopy measurements.

In this work, high-quality FASnI3 (FA, formamidinium) lead-free perovskite thin films are successfully incorporated in a flexible polyethylene terephthalate (PET) substrate to demonstrate amplified spontaneous emission (ASE) and lasing. The waveguide (WG) consists of polymethylmethacrylate(PMMA)/FASnI3 bilayer deposited on a PET substrate and is properly designed to allow single-mode propagation at the photoluminescence wavelength. This geometry optimizes the excitation of the emitting FASnI3, enhances the light−matter interaction in the semiconductor thin film, provides a preferable direction for the emitted light and allows its direct outcoupling for on-chip or fiber-optic applications. As far as the authors know, ASE and random lasing are obtained for the first time in a flexible-based WG integrating a highly efficient lead-free perovskite. The high quality of the deposited films and the optimized design of the structure result in an extremely low ASE/lasing threshold in the range of 1 µJ cm−2, which is only ten times higher than that measured in the same PMMA/FASnI3 structure deposited on a rigid substrate (Si/SiO2). More interestingly, these WGs exhibit a strong polarization anisotropy for the outcoupled ASE/lasing light with a preferable transverse electric polarization. This work is the base for the future development of ecofriendly, flexible, and efficient photonic devices. ; This project received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 862656 (project DROP-IT) and the European Research Council (ERC) via Consolidator Grant (724424, No-LIMIT) and by the Spanish MINECO through projects no. PID2020-120484RB-I00 and PID2019-107314RB-I00 (Stable).

Despite the large photovoltaic performance recently achieved, many aspects of the working principles of hybrid organic–inorganic perovskite solar cells remain to be unveiled. We analyze the experimental features observed in the decay of photovoltage and provide an interpretation of the different depolarization regimes at distinct time scales. We introduce an instantaneous relaxation time that shows the type of relaxation for each separate mechanism. The decay of photovoltage is characterized by electronic events at the ms time scale followed by a power law relaxation in the 10–100 s time window. The latter process is associated with the slow dielectric relaxation of CH3NH3PbI3 perovskite and it points to cooperative kinetics of polarization and depolarization of ferroelectric domains. These findings provide an important tool for interpretation of kinetic features in the perovskite ferroic solar cells. ; The research leading to these results has received funding from the European Union Seventh Framework Program [FP7/2007 – 2013] under grant agreement 316494, MINECO of Spain under project MAT2013-47192-C3-1-R, Generalitat Valenciana (project ISIC/2012/008) and the National Research Foundation of Korea (NRF) grants funded by the Ministry of Science, ICT & Future Planning (MSIP) of Korea under contract no. NRF- 2012M3A6A7054861 (Global Frontier R&D Program on Center for Multiscale Energy System). HW Han and LF Liu acknowl- edge  nancial support from the National Natural Science Foundation of China (91433203, 61474049) and the Ministry of Science and Technology of China (863, SS2013AA50303).