Molecular exchange and passivation at interface afford high-performing perovskite solar cells with efficiency over 24%

The interface is crucial for perovskite solar cells(PSCs).However,voids at interfaces induced by the trapped hygroscopic dimethyl sulfoxide(DMSO)can reduce charge extraction and accelerate the film degradation,seriously damaging the efficiency and stability.In this work,4,4’-dinonyl-2,2’-dipyridine(DN-DP),a Lewis base with long alkyl chains is introduced to solve this problem.Theoretical calculated and experimental results confirm that the dipyridyl group on DN-DP can more strongly coordinate with Pb^(2+)than that of the S=O group on DMSO.The strong coordination effect plays a crucial role in removing the DMSO-based adduct and reducing the formation of voids.Due to the electron-donating properties of pyridine,the existence of DN-DP in the perovskite film can passivate the defects and optimize the energy level alignment of the perovskite configuration.The open-circuit voltage(VOC)of the DN-DP-based PSC is improved from 1.107 V(control device)to 1.153 V,giving rise to a power conversion efficiency(PCE)of24.02%.Furthermore,benefiting from the moisture resistance stemming from the hydrophobic nonyl group,the PCE retains 90.4%of the initial performance after 1000 h of storage in the ambient condition.

Improved crystallinity and self-healing effects in perovskite solar cells via functional incorporation of polyvinylpyrrolidone

Air moisture is the key issue for perovskites which invades the films and accelerates the damage of devices. Here, polyvinylpyrrolidone(PVP) is introduced to the methylammonium lead iodide(MAPbI_(3)) perovskite precursor to control crystal growth and endow the devices with self-healing ability in a moisture environment. The strong C=O...ΗAΝ hydrogen bonding interactions between PVP and MAPbI_(3) was confirmed by nuclear magnetic resonance measurements. By introducing hydrogen bonding in the MAPbI_(3)-based PSCs, we form a compact perovskite film of excellent electronic quality with a power conversion efficiency(PCE) of up to 20.32%. Furthermore, the O...ΗAΝ hydrogen bonding interactions at the grain boundaries suppress the decomposition of methylammonium cations and improve the recyclable dissolution–recrystallization of perovskite. As a result, the MAPbI_(3)-PVP based cells exhibited striking moisture stability and self-healing behavior, with negligible decay in efficiency after 500 h of operation in high humidity(65% ± 5% relative humidity) and rapid recovering ability after their removal from the humid environment.

Localized Electrons Accelerated Ionic and Charge Transfer for Superior Lithium Storage

The electrochemical energy storage performance is greatly determined by the charge transfer and ion transportation occurring in the electrode materials.Therefore,the enhancement of electric conductivity and ionic mobility is vital for high-performing and stable metal ion batteries.Here,we report the properties of oxygen vacancies(VO)and carbon co-doped TiO_(2) hollow spheres(HS-TiO_(2))and compared them with fully oxidized white TiO_(2) hollow spheres(W-TiO_(2)).Theoretical calculations and experimental results revealed that the introduction of carbon dopant and VO in anatase TiO_(2) reduced the bandgap and the existence of localized electrons,leading to a lower migration barrier of Li ions that promoted faster ion diffusion kinetics,enabling the HS-TiO_(2) with higher reversibility during the insertion and extraction of Li ions than the W-TiO_(2).This HS-TiO_(2) delivered superior lithium storage properties with a specific discharge capacity of 214.6 mAh g^(-1) for the 100th cycle at 200 mA g^(-1) and 116.3 mAh g^(-1) over 2000 cycles at a high rate of 2 A g^(-1).

Surface Active Sites on Co_(3)O_(4) Nanobelt and Nanocube Model Catalysts for CO Oxidation

CO oxidation has been performed on Co_(3)O_(4) nanobelts and nanocubes as model catalysts.The Co_(3)O_(4) nanobelts which have a predominance of exposed{011}planes are more active than Co_(3)O_(4) nanocubes with exposed{001}planes.Temperature programmed reduction of CO shows that Co_(3)O_(4) nanobelts have stronger reducing properties than Co_(3)O_(4) nanocubes.The essence of shape and crystal plane effect is revealed by the fact that turnover frequency of Co3+sites of{011}planes on Co_(3)O_(4) nanobelts is far higher than that of{001}planes on Co_(3)O_(4) nanocubes.

Inside-out Ostwald ripening： A facile process towards synthesizing anatase TiO2 microspheres for high- efficiency dye-sensitized solar cells

一灵巧在内外面，到 TiO 2 microspheres 的控制形态学的准备的 Ostwald 成熟线路被开发。这里， TiO 2 空 microspheres (HM ) 和稳固的 microspheres (SM ) 被在 solvothermal 过程以 acetylacetone (Acac ) 调整 isopropanol (国际语音学协会) 的体积比率准备。在 HM，稳固的核心的降水，核心的表面上的外部壳的随后的免职，和同时的核心的形成过程期间，溶解和壳再结晶被观察，它验证在内外面 Ostwald 成熟机制。TiO 2 microspheres 的性质(毛孔尺寸，表面区域，和陷井状态) 的设计和优化对 dyesensitized 太阳能电池(DSSC ) 的高效重要。优化 TiO 2 microspheres (rHM 和 rSM ) 在再结晶上由 processing 以后获得了，拥有大毛孔尺寸，高表面区域和减少的陷井状态(Ti 3+ 和氧空缺) ，并且因此是为光电的设备的理想的材料。用 rHM photoanode 制作的 DSSC 的力量变换效率是 11.22% ，它显著地与基于 rSM 的 DSSC 的 10.54% 效率相比被改进。我们的工作为综合提供策略 TiO 2 microspheres 同时提供不同物理性质以表面区域， crystallinity，形态学，和 mesoporosity。

BiVO_4 semiconductor sensitized solar cells

Semiconductor sensitized solar cells(SSSCs) are promising candidates for the third generation of cost-effective photovoltaic solar cells and it is important to develop a group of robust, environment-friendly and visible-light-responsive semiconductor sensitizers. In this paper, we first synthesized bismuth vanadate(Bi VO4) quantum dots by employing facile successive ionic layer adsorption and reaction(SILAR) deposition technique, which we then used as a sensitizer for solar energy conversion. The preliminary optimised oxide SSSC showed an efficiency of 0.36%, nearly 2 orders of magnitude enhancement compared with bare Ti O2, due to the narrow bandgap absorption of Bi VO4 quantum dots and intimate contact with the oxide substrate. This result not only demonstrates a simple method to prepare Bi VO4 quantum dots based solar cells, but also provides important insights into the low bandgap oxide SSSCs.

Synergistic effect of TiO_2 hierarchical submicrospheres for high performance dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSCs) could be improved by using rationally designed mesoporous film structure for electron collection, dye adsorption and light scattering. The development of a novel double layer film prepared by TiO_2 hierarchical submicrospheres and nanoparticles was reported in this article. The submicrospheres were composed of rutile nanorods of 10 nm diameter and the length of 150–250 nm, which facilitated fast electron transport, charge collection and light scattering. Using a double layer structure consisting of the 10 wt% film as a dye loading layer and the 50 wt% film as the light scattering layer, C101 sensitizer and liquid electrolyte, DSC yielded power conversion efficiency of 9.68% under 1 sun illumination.