Pressure Effects on the Charge Carrier Transportation of BaF_2 Nanocrystals

The charge transport behavior of barium fluoride nanocrystals is investigated by in situ impedance measurement up to 35 GPa. It is found that the parameters change discontinuously at about 6.9 GPa, corresponding to the phase transition of BaF2 nanocrystals under high pressure. The charge carriers in BaF2 nanocrystals include both Fions and electrons. Pressure makes the electronic transport more difficult. The defects at grains dominate the electronic transport process. Pressure could make the charge-discharge processes in the Fm3m phase more difficult.

Organic Photovoltaic Cells with Improved Performance Using Bathophenanthroline as a Buffer Layer

The role of bathophenanthroline （Bphen） as a buffer layer inserted between fullerene （C60） and Ag cathode in organic photovoltaic （OPV） cell was discussed. By introducing Bphen as a buffer layer with thicknes from 0 to 2.5 nm, the power conversion efficiency of the OPV cell based on copper phthalocyanine （CuPc） and C60 was increased from 0.87% to 2.25% under AM 1.5 solar illumination at an intensity of 100 mW/cm^2, which was higher than that of bathocuproine used as a buffer layer. The photocurrent-voltage characteristics showed that Bphen effectively improves electron transport through C60 layer into Ag electrode and leads to balance charge carrier transport capability. The influence of Bphen thickness on OPV cells was also investigated. Furthermore, the absorption spectrum shows that an additional Bphen layer enhances the light harvest capability of CuPc/C60.

Embedding laser generated GaAs nanocrystals in perovskite wires for enhanced charge transport and photodetection

Solution-processed perovskite wires are attractive candidates for photodetectors(PDs)due to their simple processibility as well as one-dimensional(1D)geometry with desirable charge carrier transport.However,the performance of the perovskite PDs is generally restricted by the charge carrier transport and extraction efficiency.Herein,we demonstrate that the charge transport and the consequent photodetection performance of MAPbI_(3)perovskite wires can be effectively enhanced by incorporating nanocrystals(NCs)of GaAs-a semiconductor with high charge carrier mobility.Taking advantage of the pulsed laser irradiation technique,we successfully fabricate ligand-free GaAs NCs with a size of~7 nm and homogeneously embed them in MAPbI_(3) perovskite wires through a simple solution-processed synthesis route.Compared with the pristine perovskite wires,the GaAs NCs modulated perovskite wires show improved charge carrier transport with the mobility rising from 1.13 to 3.67 cm^(2)V^(-1)s^(-1),and the resultant PD shows significant improvement in responsivity and detectivity.This study provides a new strategy for improving optoelectronic properties of halide perovskite materials and optimizing the device performance.

How to get high-efficiency lead chalcogenide quantum dot solar cells?

Lead chalcogenide colloidal quantum dots(CQDs)are regarded as attractive absorption materials for novel solar cells(SCs).The cost of lead chalcogenide CQD has been decreased to a commercialization target of$5/g due to the direct production of CQD inks.However,the photoelectric conversion efficiency(PCE)of lead chalcogenide CQDSCs is presently close to 14%,well below the commercialization target(20%),which is only 41%of the theoretical Shockley-Queisser limit efficiency.In this study,the different losses of open-circuit voltage(V_(oc)),fill factor(FF),and short circuit current density(J_(sc))for current CQDSCs are systematically discussed,as well as the percentage and likely causes of each loss.Then the primary reasons for the CQDSCs’performance constraints are highlighted.Following that,we focus on the CQDSCs interfaces(i.e.,CQD/CQD,CQD/HTL,and ETL/CQD)and explore viable ways to reduce device performance loss.Finally,based on the discussion above,we propose many enhancements to significantly solve numerous major obstacles impeding device performance to boost the PCE of CQDSCs for future commercialization significantly.

Efficiency enhancement of P3HT:PCBM polymer solar cells using oligomers DH4T as the third component

We assembled a ternary blend bulk heterojunction polymer solar cell(PSCs) containing P3HT(donor) and PC61BM(acceptor) incorporated with a small molecule oligomer, dihexyl-quaterthiophene(DH4T) as a third component. By optimizing the contents of DH4 T, we increased the power conversion efficiency of ternary P3HT:DH4T:PC61BM PSCs to 4.17% from 3.44% of binary P3HT:PC61BM PSCs under AM 1.5 G of 100 m W/cm2 intensity. The major improvement is from the increase of the short circuit current and fill factor that is due to the increased light absorption at short wavelength, the balanced charge carrier transportation and the enhanced hole evacuation by a DH4T-enriched layer at the anode interface. In this work, we demonstrated that the efficiency of the PSCs can be enhanced by using low-bandgap conjugated polymer and its oligomer as donors and fullerene derivatives as acceptors.

Improved efficiency of ternary the blend polymer solar cells by doping a narrow band gap polymer material

A series of P3HT：PC71BM polymer solar cells （PSCs） with different PIDTDTQx doping concentrations were fabricated to in- vestigate the effect of the PIDTDTQx as a complementary electron donor on the performance of PSCs. The power conversion efficiency （PCE） of the optimized ternary blend PSCs （with 2 wt% PIDTDTQx） reached 3.87%, which is 28% higher than that of the PSCs based on P3HT：PCvlBM （control cells）. The short-circuit current density （J^c） was increased to 10.20 mA/cm2 compared with the control cells. The PCE improvement could be attributed to more photon harvest and charge carrier transport by appropriate doping PIDTDTQx. The energy transfer from P3HT to PIDTDTQx was demonstrated from the 650 nm emis- sion intensity decrease and the red-shifted emission peaks from 725 nm to 737 nm along with the increase of PIDTDTQx dop- ing concentrations.