Perovskite Self-Passivation with PCBM for Small Open-Circuit Voltage Loss

It is well known that [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is a common n-type passivation material in PSCs, usually used as an interface modification layer. However, PCBM is extremely expensive and is not suitable for future industrialization. Herein, the various concentrations of PCBM as an additive are adopted for PSCs. It not only avoids the routine process of spin coating the multi-layer films, but also reduces the PCBM material and cost. Meanwhile, PCBM can passivate the grain surface and modulate morphology of perovskite films. Furthermore, the most important optical parameters of solar cells, the current density (Jsc), fill factor (FF), open-circuit voltage (Voc) and power conversion efficiencies (PCE) were improved. Especially, when the PCBM doping ratio in CH3NH3PbI3 (MAPbI3) precursor solution was 1 wt%, the device obtained the smallest Voc decay (less than 1%) in the p-i-n type PSCs with poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) as hole transport layer (HTL) and fullerene (C60) as electron transport layer (ETL). The PSCs Voc stability improvement is attributed to enhanced crystallinity of photoactive layer and decreased non-radiative recombination by PCBM doping in the perovskites.

The fabrication of AlN by hydride vapor phase epitaxy

Aluminum nitride(AlN)is the promising substrates material for the epitaxial growth ofⅢ-nitrides devices,such as high-power,high-frequency electronic,deep ultraviolet optoelectronics and acoustic devices.However,it is rather difficult to obtain the high quality and crack-free thick AlN wafers because of the low surface migration of Al adatoms and the large thermal and lattice mismatches between the foreign substrates and AlN.In this work,the fabrication of AlN material by hydride vapor phase epitaxy(HVPE)was summarized and discussed.At last,the outlook of the production of AlN by HVPE was prospected.

Vanadyl Sulfate Based Hole-Transporting Layer Enables Efficient Organic Solar Cells

It remains an urgent task to develop alternative hole-transporting layer(HTL)materials beyond commonly used PEDOT:PSS to increase the shelf-life of organic solar cells(OSCs).Inorganic metal oxide type materials,such as NiO_(x),CoO_(x)and VO_(x),with suitable work functions have attracted numerous research attention recently.In this work,more abundant and easily accessible oxygenated salt,vanadyl sulfate(VOSO_(4))has been demonstrated to be excellent choice as HTL for OSCs.The VOSO_(4)-based HTL can be readily processed by spin-coating from the precursor solution with subsequent thermal annealing and UVO treatment.As a consequence,a high power conversion efficiency(PCE)of 18.72%can be achieved for PM8:L8-BO based OSCs with the VOSO_(4)-based HTL.High transmittance,smooth film surface,suitable energy level and high conductivity were revealed to contribute to the high OSC performance.More importantly,compared to device with PEDOT:PSS,VOSO_(4)-based OSCs exhibit improved stability when stored in the N_(2)filled glove box.After being stored for 600 h,VOSO_(4)-based device can retain 89%of its initial efficiency.Notably,VOSO_(4)can be used as general HTL in PM6:BTP-BO-4Cl and PM6:IT-4F based OSCs,yielding high PCEs of 17.87%and 13.85%,respectively.

Effect of doping Gd^(3+) on crystal structure and luminescent properties of Sr_2SiO_4:Eu^(2+) phosphor

Sr1.995-1.5xGdxSiO4：0.005Eu^2＋ phosphor series with x=0-0.08 mol for near-ultraviolet white light-emitting diodes （NUV w-LEDs） were synthesized via solid-state reaction method. XRD profile pattern and refinement results demonstrated that doping Gd^3＋ ions resulted in the phase transformation （β-Sr2SiO4→α＇-Sr2SiO4）. The photoluminescenee spectrum of the sample with x=0 tool displayed two emission peaks centered at 470 and 525 nm. The two-peak spectra became one-peak spectra with the Gd^3＋ concentration increasing. Actually, the fitting results demonstrated that the one-peak spectra were still composed of two single emission spectra. The photoluminescence intensity was improved and the CIE chromaticity coordinates were adjusted via doping Gd^3＋.