CsPbI_(2)Br-based perovskite solar cells(PSCs)have attracted much attention because of their excellent phase stability and appropriate bandgap.However,numerous defects of undercoordinated ions or mobile species are th...CsPbI_(2)Br-based perovskite solar cells(PSCs)have attracted much attention because of their excellent phase stability and appropriate bandgap.However,numerous defects of undercoordinated ions or mobile species are the sites of carrier nonradiative recombination,causing a low power conversion efficiency(PCE).In this work,NaCl and nitrogen-doped graphene quantum dots(N-GQDs)as binary additives are introduced into perovskite precursor to obtain high-quality photoactive films.Chloride ion(Cl^(-))is incorporated into perovskite due to the same physical and chemical properties as bromine(Br^(-)),that align the energy level of CsPbI_(2)Br,decrease the energy barrier between perovskite and P3HT to promote carrier transport and extraction,hence result in the reduced energy loss.Meanwhile,because of its good conductivity,N-GQDs at grain boundaries can rapidly conduct photogenerated electrons to SnO_(2),suppressing carrier recombination at grain boundaries.Furthermore,the trap state density of the CsPbI_(2)Br film with binary additives is reduced,which could prolong the carrier lifetime,and improve surface morphology.As a result,a PCE of 15.37%for CsPbI_(2)Br PSCs with binary additives is obtained,which shows~22.76%relative increment compare with the pristine PSCs.Therefore,a simple and convenient optimization strategy of binary additives for PSCs is proposed in this work.展开更多
基金This research was supported by the National Natural Science Foundation of China(No.61804070 and 11674138)the Science and Technology Projects of Gansu Province(No.20JR10RA611 and 21JR7RA467)the Fundamental Research Funds for the Central Universities(No.lzujbky-2021-60 and lzujbky-2021-sp54).
文摘CsPbI_(2)Br-based perovskite solar cells(PSCs)have attracted much attention because of their excellent phase stability and appropriate bandgap.However,numerous defects of undercoordinated ions or mobile species are the sites of carrier nonradiative recombination,causing a low power conversion efficiency(PCE).In this work,NaCl and nitrogen-doped graphene quantum dots(N-GQDs)as binary additives are introduced into perovskite precursor to obtain high-quality photoactive films.Chloride ion(Cl^(-))is incorporated into perovskite due to the same physical and chemical properties as bromine(Br^(-)),that align the energy level of CsPbI_(2)Br,decrease the energy barrier between perovskite and P3HT to promote carrier transport and extraction,hence result in the reduced energy loss.Meanwhile,because of its good conductivity,N-GQDs at grain boundaries can rapidly conduct photogenerated electrons to SnO_(2),suppressing carrier recombination at grain boundaries.Furthermore,the trap state density of the CsPbI_(2)Br film with binary additives is reduced,which could prolong the carrier lifetime,and improve surface morphology.As a result,a PCE of 15.37%for CsPbI_(2)Br PSCs with binary additives is obtained,which shows~22.76%relative increment compare with the pristine PSCs.Therefore,a simple and convenient optimization strategy of binary additives for PSCs is proposed in this work.
