Defect passivation of functional additives is an effective approach to suppress the nonradiative recombination centers in perovskite solar cells. Here, a symmetrical conjugated molecular additive (4,4′-bipyridyl, BPY­[4,4]) with bilateral nitrogen atoms is employed for effective defect passivation by bonding with uncoordinated Pb2+ cations within perovskite. Meanwhile, π-conjugated BPY­[4,4] affords large bridging interaction for better charge carrier transfer pathway between perovskite grains than control, as witnessed by increased electron and hole mobility. Consequently, the device with optimal BPY­[4,4] device displays a power conversion efficiency of 20.82% higher than control device of 18.38% and exhibits better long-term thermal stability. It is worth noting that BPY­[4,4] has symmetrical and conjugated molecular structures, which benefit from π–π stacking and face-on orientation structure, so it has more advantages than asymmetric and nonconjugated molecular additives, such as charge transfer, defect passivation, and device performance. Our work demonstrates that symmetrical conjugated molecule additives can construct bridged charge transfer channels between perovskite grains as well as effective defect passivation.

No abstract

No abstract

In this paper, we describe the performance of an organic light emitting devices〔OLEDs〕 with ITO /4,4’,4“-tris{N,- （ 3-methylphenyl ） -N-phenylamino}triphenylamine (m-MTDATA) /N,N-diphenyl-N,N-bis1-naphthyl-1,1-biphenyl-4,4-diamine (NPB) /copper phthalocyanine (CuPc) / NPB / Bathocuproine(BCP) / tris-8-hydroxyquinoline Aluminum (Alq3) / LiF/ AL structure, the CuPc inserted between the two layers of NPB as a hole-consuming layer (HCL), and the BCP as a hole-blocking layer (HBL) . The EL spectrum peak is at 430 nm, indicating that the carrier recombination is confined in the NPB layer, in additional light emission originates from NPB. Compared with the luminous efficiency of the conventional diode without CuPc layer, that of the diode with HCL has been sharply increased up to 2.62 cd /A. It suggested that the CuPc and BCP exactly function as hole-consuming and hole-blocking layers, respectively, which enhance the efficiency of carrier，s recombination and confine the excitation in the EL layer.

No abstract