In this perspective, we present strategies that foster the expulsion of lead from perovskites to obtain a non-hazardous active material.

The use of divalent chalcogenides and monovalent halides as anions in a perovskite structure allows the introduction of 3 and 4 charged cations in the place of the 2 metal cations. Herein we report for the first time on the fabrication of solar cells exploiting methylammonium antimony sulfur diiodide (MASbSI) perovskite structures, as light harvesters. The MASbSI was prepared by annealing under mild temperature conditions, via a sequential reaction between antimony trisulfide (SbS), which is deposited by the chemical bath deposition (CBD) method, antimony triiodide (SbI), and methylammonium iodide (MAI) onto a mesoporous TiO electrode, and then annealed at 150 °C in an argon atmosphere. The solar cells fabricated using MASbSI exhibited power conversion efficiencies (PCE) of 3.08%, under the standard illumination conditions of 100 mW/cm.

Although antimony sulfoiodide (SbSI) exhibits very interesting properties including high photoconductivity, ferroelectricity, and piezoelectricity, it is not applied to solar cells. Meanwhile, SbSI is predominantly prepared as a powder using a high‐temperature, high‐pressure system. Herein, the fabrication of solar cells utilizing SbSI as light harvesters is reported for the first time to the best of knowledge. SbSI is prepared by solution processing, followed by annealing under mild temperature conditions by a reaction between antimony trisulfide, which is deposited by chemical bath deposition on a mesoporous TiO2 electrode and antimony triiodide, under air at a low temperature (90 °C) without any external pressure. The solar cells fabricated using SbSI exhibit a power conversion efficiency of 3.05% under standard illumination conditions of 100 mW cm−2.

Photodetectors with high photoelectronic gain generally require a high negative working voltage and a very low environment temperature. They also exhibit low response speed and narrow linear dynamic range (LDR). Here, an organic photodiode is demonstrated, which shows a large amount of photon to electron multiplication at room temperature with highest external quantum efficiency (EQE) from ultraviolet (UV) to near-infrared region of 5.02 × 10 % (29.55 A W ) under a very low positive voltage of 1.0 V, accompanied with a fast response speed and a high LDR from 10 to 10 mW cm . At a relatively high positive bias of 10 V, the EQE is up to 1.59 × 10 % (936.05 A W ). Inversely, no gain is found at negative bias. The gain behavior is exactly similar to a bipolar phototransistor, which is attributed to the photoinduced release of accumulated carriers. The devices at a low voltage exhibit a normalized detectivity (D*) over 10 Jones by actual measurements, which is about two or three order of magnitudes higher than that of the highest existing photodetectors. These pave a new way for realization of high sensitive detectors with fast response toward the single photon detection.

No abstract

Growing interest in hybrid organic-inorganic lead halide perovskites has led to the development of various perovskite nanowires (NWs), which have potential use in a wide range of applications, including lasers, photodetectors, and light-emitting diodes (LEDs). However, existing nanofabrication approaches lack the ability to control the number, location, orientation, and properties of perovskite NWs. Their growth mechanism also remains elusive. Here, we demonstrate a micro/nanofluidic fabrication technique (MNFFT) enabling both precise control and in situ monitoring of the growth of perovskite NWs. The initial nucleation point and subsequent growth path of a methylammonium lead iodide-dimethylformamide (MAPbI·DMF) NW array can be guided by a nanochannel. In situ UV-vis absorption spectra are measured in real time, permitting the study of the growth mechanism of the DMF-mediated crystallization of MAPbI. As an example of an application of the MNFFT, we demonstrate a highly sensitive MAPbI-NW-based photodetector on both solid and flexible substrates, showing the potential of the MNFFT for low-cost, large-scale, highly efficient, and flexible optoelectronic applications.

Covalent organic frameworks (COFs) as a new class of crystalline, porous materials have attracted extensive attention in the fields of photocatalytic and photovoltaic applications. Generally, donor-acceptor (DA) structures play an important role in the charge separation efficiency of solar cells. In this study, two DA-COFs with high crystallinity, good porosity, and excellent stability are incorporated into the FAPbI 3 layer of perovskite solar cells. This addition of DA-COFs reduces the defect concentration and shallows the defect state. The donor-acceptor system in COFs also possesses strong charge-transfer pathway, which strongly prevents charge recombination to afford more efficient charge separation efficiency. The highest power-conversion efficiency of perovskite solar cells constructed with DA-COFs is 23.19% with excellent humidity stability of the solar cells. Therefore, this work provides a pathway for using DA-COFs to fabricate perovskite solar cells with higher efficiency and stability.

The passivation of electronic defects at the surfaces and grain boundaries of perovskite materials is one of the most important strategies for suppressing charge recombination in perovskite solar cells (PSCs). Although several passivation molecules have been investigated, few studies have focused on their application in regulating both the surface passivation and residual strain of perovskite films. In this study, the residual strain distribution profiles of the Cs0.1FA0.9SnI3 perovskite thin films and their effect on the photovoltaic device efficiencies were investigated. We found a gradient distribution of the out-of-plane compressive strain that correlated with the compositional inhomogeneity perpendicular to the substrate surface. By deliberately engineering dual effects of the surface passivation and residual strain, we achieved a record power conversion efficiency of up to 9.06%, the highest ever reported in a typical n–i–p architecture.