Realizing Stable High‐Performance and Low‐Energy‐Loss Ternary Photovoltaics through Judicious Selection of the Third Component

Abstract

Figure 7. Stabilities of the optimized binary and ternary devices measured a) inside a glove box and b) under exposure to ambient air (25 C, 40% humidity).

High-Performance Ternary Organic Photovoltaics Incorporating Small-Molecule Acceptors with an Unfused-Ring Core

“…The embedding of NTCPDT2F might have inhibited the aggregation of Y6 as a result of its flexible unfused-ring core, leading to a smaller blend domain size. A similar phenomenon in a previous study was observed, where greater miscibility between a host and guest acceptor led to a relatively low degree of phase segregation . NTCPDTCN might have been well dispersed in the Y6 matrix, resulting in a morphology similar to that of the binary blend.…”

“…The device based on the PM6:Y6 binary blend exhibited a J SC of 24.6 ± 0.46 mA/ cm 2 , a V OC of 0.87 ± 0.01 V, and an FF of 71.7 ± 0.64%, resulting in a PCE of 15.4 ± 0.25%, consistent with previous reports. 55,56 The ternary-blend device including NTCPDTCN exhibited a J SC of 25.5 ± 0.51 mA/cm 2 , a V OC of 0.85 ± 0.01 V, and an FF of 70.8 ± 1.01%, resulting in a PCE of 15.4 ± 0.09%. The NTCPDTID-containing ternary device exhibited a J SC of 24.3 ± 0.23 mA/cm 2 , a V OC of 0.84 ± 0.01V, and an FF of 71.8 ± 0.88%, resulting in a PCE of 14.6 ± 0.15%.…”

“…According to previous reports, a guest acceptor having a LUMO energy level higher than that of the host acceptor can lead to a decrease in energy loss, with the premise that introducing the guest acceptor could lead to effective mixing with the host acceptor. 14,56 Figure 1c displays the energy levels of PM6, Y6, 14 and the NFAs; notably, all of the NFAs had LUMO energy levels higher than that of Y6. Thus, the slight lowering of the V OC values might be attributable to the miscibility of our NFAs with Y6, including the variation in the blend morphology of its counterpart, as we discuss below.…”

“…A similar phenomenon in a previous study was observed, where greater miscibility between a host and guest acceptor led to a relatively low degree of phase segregation. 56 NTCPDTCN might have been well dispersed in the Y6 matrix, resulting in a morphology similar to that of the binary blend. The miscibility of the host/ guest acceptors and the LUMO energy level of the guest acceptor were reported to positively correlate with the V OC values of the OPVs.…”

Metal-Free Interconnecting Layer for Monolithic Perovskite/Organic Tandem Solar Cells with Enhanced Outdoor Stability

“…Although there are several perovskite material combinations for front sub-cells, back sub-cells in all-perovskite monolithic tandems are limited to using narrow band gap tin (Sn) based perovskites which are air sensitive and highly reactive due to the oxidation of Sn 2+ to Sn 4+ . − This intrinsic material property issue frustrates the ease of fabrication of such devices and limits their operational stability under ambient and outdoor conditions. Organic photoactive layers, on the contrary, offer processing under ambient conditions, − show promising device performances with tunable and ultralow band gaps, − and are shown to be stable under operational conditions. − Hence, using a combination of a wide band gap perovskite front cell, and a narrow band gap organic back cell to fabricate perovskite/organic monolithic tandem could be a solution to achieving efficient and stable solar cells. − …”