Layer-by-layer solution-process enables higher crystallinity and desirable phase separation in non-fullerene organic solar cells

Abstract

Device engineering is one of the effective ways to improve the photovoltaic performance of organic solar cells. In particular, the performance of some materials may not be poor, and morphology control is more important to make efficient charge generation and transport, and inhibit exciton recombination. In this work, LBL and conventional OSCs based on PBB-TSD donor and Y6 acceptor were prepared. Compared with conventional OSCs. The LBL process improves the dissociation of excitons, inhibits charge recombination and promotes charge transfer in the active layer. Hence, a power conversion efficiency (PCE) of 11.84% with a short-circuit current density ( J SC ) of 23.52 mA cm −2 is obtained in the LBL-type OSCs, which are both higher than that of the BHJ-type OSC (PCE = 10.77%, J SC = 21.19 mA cm −2 ). These results indicate that LBL process would be a more efficient device structure than that of BHJ with PBB-TSD:Y6 as the active layer. • The ideal p-i-n like structure for efficient OSCs can be achieved by a simple and effective LBL method. • The LBL films show more ordered molecular stacking and desirable D/A vertical phase separation. • LBL-type OSCs show a higher PCE of 11.84% with a J SC of 23.52 mA cm −2 and a FF of 59.06%. • For donors and acceptors with limited miscibility, LBL process is an ideal method for constructing OSCs with a high PCE.