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The perovskites used for optoelectronic devices have been more attractive during recent years due to their wide variety of advantages, such as their low cost, high photoluminescence quantum yield (PLQY), high carrier mobility, flexible bandgap tunability, and high light absorption ability. However, optoelectronic applications for traditional inorganic and organic materials present dilemmas due to their hardly tunable bandgap and instability. On the other hand, there are some more important benefits for perovskite nanocrystals, such as a size-dependent bandgap and the availability of anion exchange at room temperature. Therefore, perovskite NC-based applications are currently favored, offering a research direction beyond perovskite, and much research has focused on the stability issue and device performance. Thus, the synthesis and applications of perovskite NCs need to be thoroughly discussed for the future development of solar cells, light-emitting diodes, photodetectors, and laser research. [ABSTRACT FROM AUTHOR]

Abstract The solid solutions comprising amorphous conjugated polymer PCDTBT and different fullerene derivatives, i.e. crystalline PC 71 BM and amorphous NC 60 BA, have been investigated. It is found that the solid solution based on NC 60 BA could produce more hole carriers at the room temperature due to a smaller activation energy from trap state to free carriers compared to that based on PC 71 BM. A higher hole carrier density could effectively fill traps and reduce the recombination loss during charge transport process. The solid solution based on PC 71 BM shows enhanced exciton dissociation probability at the solid solution/C 60 heterojunction interfaces. With combining the advantages of both the solid solutions, a small amount of amorphous NC 60 BA was introduced into the PCDTBT:PC 71 BM bulk heterojunction structure and the ternary BHJ PSCs composed of PCDTBT, PC 71 BM and NC 60 BA were fabricated. The ternary PSCs display outstanding photovoltaic performance compared to the binary PCDTBT:PC 71 BM bulk heterojunction PSCs. Graphical abstract With the same device structure, the ternary polymer solar cells based on the PCDTBT:NC 60 BA:PC 71 BM blend demonstrate much better photovoltaic performance than the binary PCDTBT:PC 71 BM blend solar cells. Image Highlights • The electrical and photovoltaic characteristic between the PCDTBT:NC 60 BA and PCDTBT:PC 71 BM solid solution are different. • The carrier density in PCDTBT:NC 60 BA solid solution is higher than that in PCDTBT:PC 71 BM solid solution. • The measured activation energy in PCDTBT:NC 60 BA solid solution is smaller than that in PCDTBT:PC 71 BM solid solution. • The ternary PSCs based on PCDTBT:NC 60 BA:PC 71 BM blend show superior photovoltaic performance to the binary PCDTBT:PC 71 BM PSCs. [ABSTRACT FROM AUTHOR]

Abstract The solid solution phenomenon in the amorphous PCDTBT:PC 71 BM blend was investigated. It has been disclosed that the PCDTBT:PC 71 BM blend with less than 20% PC 71 BM may form a kind of solid solution structure, which demonstrates a deeper HOMO level, a higher hole mobility, more free charges and less trap density than those of the pure PCDTBT film. It may well explain why the typical PCDTBT:PC 71 BM bulk heterojunction solar cells require higher PC 71 BM ratio to achieve a high power conversion efficiency. In that case, a portion of PC 71 BM is well intermixed with PCDTBT to form a solid solution phase and others form a pure PC 71 BM phase. It is the PCDTBT:PC 71 BM solid solution but not the pure PCDTBT to serve as the donor phases and to form interpenetrating networks with PC 71 BM phases. The PCDTBT:PC 71 BM solid solution phases favor to increase the V OC and enhance the charge collection leading to a high photovoltaic performance for the PCDTBT:PC 71 BM bulk heterojunction solar cells. Graphical abstract The PCDTBT:PC 71 BM blend with less than 20% PC 71 BM may form a kind of solid solution structure, which demonstrates a deeper HOMO level, a higher hole mobility, more free charges and less trap density than those of the pure PCDTBT film. A graphical schematic illustrates the interpenetrating networks composed of the solid solution and PC 71 BM in a practical PCDTBT:PC 71 BM BHJ solar cells. Image Highlights • The existence of the solid solution comprising of PCDTBT and PC 71 BM was confirmed by UPS and CV measurement. • Electric characteristics of the solid solution was studied by the FET and the varied temperature conductivity measurement. • The difference of photovoltaic characteristics between pure PCDTBT and the solid solution were compared. [ABSTRACT FROM AUTHOR]

Polymer solar cells (PSCs) based on the PBDTTT-EFT (polymer donor):N2200 (polymer acceptor) blend have been fabricated with the active layer processed with various solvents including o -dichlorobenzene ( o -DCB), chlorobenzene (CB), chloroform (CF), and CF: p -xylene (PX) mixed solvent. A highest power conversion efficiency (PCE) of 5.37% is achieved with the active layer processed with CF:PX mixed solvent. The dependence of short-circuit current density ( J SC ) on incident light intensity indicates that the charge recombination is to some extent suppressed in the device with the active layer processed with the CF:PX mixed solvent and results in an enhanced J SC . Morphology studies disclosed that the domains are preferential face-on orientation in the active layers processed with o -DCB, CB and CF, while it shows a combined face-on and edge-on orientation in CF:PX-processed film. The long-lived trap-assisted charge recombination originated from the active layer morphological variance has been focused on and investigated. And the nanosecond transient absorption experiment further demonstrated that the PBDTTT-EFT:N2200 film processed with o -DCB shows obvious long-lived trap-assisted charge recombination, while the trap-assisted charge recombination is effectively suppressed in the PBDTTT-EFT:N2200 film processed with CF:PX mixed solvent. This implies that deep localized traps correlated with the PBDTTT-EFT:N2200 morphology are reduced by using the CF:PX mixed solvent to process the active layer. In addition, the domains with a mixed orientation in the active layer may also enhance the three-dimensional charge transport and hence improve the charge-collection efficiency. [ABSTRACT FROM AUTHOR]