Silicon heterojunction solar cells have shown great advantage due to their large open-circuit voltage which induces a high energy conversion efficiency. However, the short-circuit current density is limited by the high light absorption of an n-type amorphous silicon window layer in the short-wavelength range. Here an amorphous silicon oxide film was introduced to replace the window layer. The increasing oxygen content in amorphous silicon oxide layers leads to the enlarged optical band gap and the enhanced short-wavelength transmittance. As a result, the short-circuit current density increases obviously which comes from the high transmittance of amorphous silicon oxide films due to the wider band gap. Furthermore, the highly phosphorous-doped amorphous silicon layer was introduced to improve the contact between transparent conductive oxide layer and n-type amorphous silicon oxide layer. The carrier transport property is enhanced and thus the fill factor increases significantly. Finally, a silicon heterojunction solar cell with an area of 238.95 cm2 was prepared, yielding a total-area efficiency up to 21.1%. Overall, the results indicate that amorphous silicon oxide films can be applied to silicon heterojunction solar cells as a window layer, which provides a new route to obtain higher energy conversion efficiency.

•Mesoporous carbon (MC) is prepared by carbonization of zeolitic imidazolate frameworks-8.•MC is used as additive in modifying commercial LiFePO4 (LFP) by simple physical mix.•LFP@MC cathode exhibits high rate performance and high capacity retention ratio.In order to improve high rate and cycle performances of commercial LiFePO4 (LFP), mesoporous carbon (MC) is synthesized by carbonization of zeolitic imidazolate frameworks-8 (ZIF-8). As an additive, MC can improve both electronic conductivity and lithium ion diffusion coefficient of LFP due to its high conductivity and mesoporous structure. LFP mixing with MC delivers a high rate performance of 154.6 mAh g−1 at a current rate of 0.5 C and a capacity retention ratio of approximately 99.9% after 60 cycles at 10.0 C. Moreover, the discharge energy density is also improved due to the enhancement of discharge voltage platform.

•Er, Yb co-dopedYF3 upconversion films have been successfully prepared.•The upconversion property can be modulated by morphology and crystallinity.•The upconversion transparent YF3 films are promising for solar cells applications.Highly transparent Er, Yb codoped YF3 upconversion films were successfully prepared by electron beam deposition method. The effects of the substrate temperature on the morphology, crystallinity and emission characteristics of Er, Yb codoped YF3 films were studied carefully. It was found that the morphology and crystallinity varied from smooth amorphous to root-intertwined polycrystalline structure with the substrate temperature increase. Besides, the emission characteristics of the films can be modulated by the synergy of their surface morphologies and crystallinities. Remarkably, a large enhancement of the upconversion emission, up to five decades while only an insignificant decrease of the optical transmittance (10% at most), was achieved by forming root-intertwined polycrystalline structures. These highly transparent upconversion films may have good potential for enhancing the conversion efficiency of wide band-gap solar cells.

By a pulsed laser deposition technique the efficient broadband near-infrared downconversion Bi–Yb codoped crystallization Y2O3 transparent films have been grown successfully on Si (1 0 0) substrates. Upon excitation of ultraviolet photon varying from 300 to 400 nm, the near infrared quantum cutting has been obtained, which is originated from the transitions of the transition-metal Bi3+ 3P1 level to Yb3+ 2F5/2 level. The downconversion quantum efficiency of films is estimated to be 152%. The transparent Y2O3 films may have potential application in enhancing the conversion efficiency of crystalline Si solar cells.Highlights► The downconversion Y2O3:Bi,Yb films has good transparency. ► Y2O3:Bi,Yb films possess a broadband absorption in the UV region of 300–400 nm. ► The films may have potential application in enhancing the efficiency of c-Si cells.

We investigated the tunable resonant tunneling through a system of capacitively coupled double quantum dots (CDQDs) in series with interdot tunneling. According to the linear regime, it is found that the presence of the interdot Coulomb repulsion destroys the symmetry of the two groups of conductance peaks located around resonant states. Moreover, it also shows that the influence of the interdot interaction on the resonant tunneling in the weaker tunneling coupling case is obviously different from that in the stronger tunneling coupling case. These results indicate that the coexistence of quantum and classical effects present novel properties for electron resonant tunneling the CDQD system. In addition, for the asymmetric capacitively CDQDs, the effect of the interdot capacitive and tunneling coupling on the resonant tunneling is also discussed in detail.