Polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are fabricated by using 1,8-diiodooctane (DIO) as a solvent additive to control the dop...Polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are fabricated by using 1,8-diiodooctane (DIO) as a solvent additive to control the doping density of the PSCs. It is shown that the processing of DIO does not change the doping density of the P3HT phase, while it causes a dramatic reduction of the doping density of the PCBM phase, which decreases the doping density of the whole blend layer from 3.7 × 10^16 cm-3 to 1.2 ×10^16 cm-3. The reduction of the doping density in the PCBM phase originates from the increasing crystallinity of PCBM with DIO addition, and it leads to a decreasing doping density in the blend film and improves the short circuit current of the PSCs.展开更多
The donor:acceptor(D:A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction(BHJ) orga nic solar cells(OSCs).The proper D:A blend ratio can pr...The donor:acceptor(D:A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction(BHJ) orga nic solar cells(OSCs).The proper D:A blend ratio can provide maximized D/A interfacial area for exciton dissociation and appro p riate domain size of the exciton diffusion length,which is beneficial to obtain high-performance OSCs.Here,we comprehensively investigated the relationship between various D:A blend ratios and the charge transfer and energy transfer mechanisms in OSCs based on PBDB-T and non-fullerene acceptor IT-M.Based on various D:A blend ratios,it was found that the ratio of components is a key factor to suppress the formation of triplet states and recombination energy losses.Rational D:A blend ratios can provide appropriate donor/accepter surface for charge transfer which has been powerfully verified by various detailed experimental results from the time-resolved fluorescence measurement and transient absorption(TA) spectroscopy.Optimized coherence length and crystallinity are verified by grazing incident wide-angle X-ray scattering(GIWAXS) measurements.The results are bene ficial to comprehend the effects of various D:A blend ratios on charge transfer and energy transfer dynamics and provides constructive suggestions for rationally designing new materials and feedback for photovoltaic performance optimization in non-fullerene OSCs.展开更多
We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fr...We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons(holes)in the device are collected by anode(cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination(BR)or geminate recombination(GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same.Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.展开更多
基金Supported by the National Natural Science Foundation of China under Grant Nos 21174016 and 11474017the Doctoral Program of Higher Education of China under Grant No 20120009110031
文摘Polymer solar cells (PSCs) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are fabricated by using 1,8-diiodooctane (DIO) as a solvent additive to control the doping density of the PSCs. It is shown that the processing of DIO does not change the doping density of the P3HT phase, while it causes a dramatic reduction of the doping density of the PCBM phase, which decreases the doping density of the whole blend layer from 3.7 × 10^16 cm-3 to 1.2 ×10^16 cm-3. The reduction of the doping density in the PCBM phase originates from the increasing crystallinity of PCBM with DIO addition, and it leads to a decreasing doping density in the blend film and improves the short circuit current of the PSCs.
基金supported by the National Natural Science Foundation of China(Nos.11774204,11804084)Major Program of Natural Science Foundation 25 of Shandong Province(No.ZR2019ZD43)+2 种基金the Fundamental Research Funds of Shandong University(No.2018JC034)support from the ARC Centre of Excellence in Exciton Science(No.CE170100026)the Shanghai Synchrotron Radiation Facility(beamline BL16B1)for providing the beam time for GIWAXS measurements。
文摘The donor:acceptor(D:A) blend ratio plays a very important role in affecting the progress of charge transfer and energy transfer in bulk heterojunction(BHJ) orga nic solar cells(OSCs).The proper D:A blend ratio can provide maximized D/A interfacial area for exciton dissociation and appro p riate domain size of the exciton diffusion length,which is beneficial to obtain high-performance OSCs.Here,we comprehensively investigated the relationship between various D:A blend ratios and the charge transfer and energy transfer mechanisms in OSCs based on PBDB-T and non-fullerene acceptor IT-M.Based on various D:A blend ratios,it was found that the ratio of components is a key factor to suppress the formation of triplet states and recombination energy losses.Rational D:A blend ratios can provide appropriate donor/accepter surface for charge transfer which has been powerfully verified by various detailed experimental results from the time-resolved fluorescence measurement and transient absorption(TA) spectroscopy.Optimized coherence length and crystallinity are verified by grazing incident wide-angle X-ray scattering(GIWAXS) measurements.The results are bene ficial to comprehend the effects of various D:A blend ratios on charge transfer and energy transfer dynamics and provides constructive suggestions for rationally designing new materials and feedback for photovoltaic performance optimization in non-fullerene OSCs.
基金Project supported by the Natural Science Foundation of Hebei Province,China(Grant No.A2012203016)the Science Fund from the Education Department of Hebei Province,China(Grant Nos.QN20131103 and Z2009114)+1 种基金the Doctor Foundation of Yanshan University,China(Grant No.B580)the Young Teachers’Research Project of Yanshan University,China(Grant No.13LGB028)
文摘We use the method of device simulation to study the losses and influences of geminate and bimolecular recombinations on the performances and properties of the bulk heterojunction organic solar cells. We find that a fraction of electrons(holes)in the device are collected by anode(cathode). The direction of the corresponding current is opposite to the direction of photocurrent. And the current density increases with the bias increasing but decreases as bimolecular recombination(BR)or geminate recombination(GR) intensity increases. The maximum power, short circuit current, and fill factor display a stronger dependence on GR than on BR. While the influences of GR and BR on open circuit voltage are about the same.Our studies shed a new light on the loss mechanism and may provide a new way of improving the efficiency of bulk heterojunction organic solar cells.