To date, organic solar cells (OSCs) with the development of photovoltaic materials have realized high power conversion efficiencies (PCEs) through the solution processing strategy with bulk heterojunction (BHJ) structure, but the BHJ morphology is difficult to control in large-scale fabrication of OSCs. Herein, we report an alternative film-forming technology known as layer-bylayer (LbL). As compared to its BHJ counterpart, LbL presents many unique advantages including controllable ''p-i-n'' morphology, good charge transport and extraction properties, and great universality. By using the LbL-bladed coating strategy, a high PCE of 16.35% was achieved in the PM6:Y6 OSCs. Notably, a large-area solar module of 11.52 cm 2 with a geometrical fill factor of over 90% exhibited an outstanding PCE of 11.86%, which represents the highest efficiency of large-area solar modules. The results may pave the way for the fabrication of the photoactive layer in the future industrial production of OSCs.

Figure 1. a) The synthetic routes of IC-Br(in) and IC-Br(out). b) Chemical structures of PY-IT, PY-OT and PY-IOT.

Asymmetric acceptor BTP-2F-ThCl-based devices gave the best PCE of 17.06% due to the optimal energy levels relative to those of the devices based on their symmetrical counterparts, BTP-4F (16.37%) and BTP-2ThCl (14.49%).