No abstract

Various cathode interface materials have been used in organic solar cells (OSCs) to realize high performance. However, most cathode interface materials have their respective weaknesses in maximizing the efficiency or stability of OSCs. Herein, three kinds of alcohol-soluble cathode interfacial materials are combined with bathocuproine (BCP) to serve as multifunctional bilayer cathode buffers for the regular OSCs, and thus greatly enhanced power conversion efficiencies over 10.11% and significantly improved device stability have been achieved. By utilizing double interlayers, both light absorption and light distribution in active layer are improved. Furthermore, double interlayers offer favorable energy-level alignment, alcohol treatment, and duplicate protection of active layer, resulting in significantly reduced leakage current, suppressed recombination, and efficient charge collection. The improved device stability is related to the blocking effect of the complex formed between BCP and the metal electrode and the additional protection effect of the underlying alcohol-soluble materials. In view of the universal use of alcohol-soluble organic electrolyte as cathode buffer layers and by courtesy of the superiority of the double cathode layers relative to the monolayer controls, the double interlayer strategy demonstrated here opens a new way to fully exploiting the potential of OSCs and is believed to be extended to a wider application.

No abstract

A fluorescence inhibitor 1-bromo-4-nitrobenzene was introduced into the PTB7-Th:PC71BM active layer to prepare an organic solar cell that exhibited a high PCE of 8.95%.

All-polymer solar cells (all-PSCs) have been intensively investigated due to their excellent thermal and mechanical stabilities. However, the efficiency of all-PSCs is still far behind that of organic solar cells (OSCs), which are based on small molecule acceptors. Improving the efficiency of all-PSCs is of great urgency. In this work, the solvent additive named p-anisaldehyde (AA) was introduced to improve the performance of all-PSCs based on PBDB-T:N2200. It is demonstrated that AA helps to form a better network interpenetrating track and more uniform phase separation. With the assistance of AA, which has both an oleophilic methoxy group and a hydrophilic aldehyde group, the interfacial contact between the donor and the acceptor (D/A) is improved, increasing the contact area at D/A and promoting efficient exciton dissociation. More importantly, AA acts as a “bridge” between the oleophilic active layer and the hydrophilic PEDOT:PSS layer, improving the interfacial compatibility between the active layer and the PEDOT:PSS layer, reducing the interfacial resistance, and facilitating the carrier transport. Finally, the all-PSCs based on PBDB-T:N2200 exhibits a superior power conversion efficiency (PCE) of 7.24% which is a record efficiency for the current all-PSCs with the same architecture. In this work, a promising and effective strategy for achieving high efficiency all-PSCs is provided.