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.

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A narrow-band-gap polymer acceptor (P A ), namely PYT, is reported, while a series of PYT polymer acceptors with controlled average molecular weight (M n ) values were synthesized for fine-tuning the molecular crystallinity and miscibility. When fabricated into all-PSCs with a polymer donor (P D ) PM6, we observed a clear M n dependence on device performance. The PM6:PYT M device gives a record-high PCE of 13.44% for the all-PSCs, resulting from the good P D -P A pair miscibility, suitable blend microstructure, and improved charge transport properties.

The thermal stability of organic solar cells is critical for practical applications of this emerging technology. Thus, effective approaches and strategies need to be found to alleviate their inherent thermal instability. Here, we show a polymer acceptor-doping general strategy and report a thermally stable bulk heterojunction photovoltaic system, which exhibits an improved power conversion efficiency of 15.10%. Supported by statistical analyses of device degradation data, and morphological characteristics and physical mechanisms study, this polymer-doping blend shows a longer lifetime, nearly keeping its efficiency (t = 800 h) under accelerated aging tests at 150 o C. Further analysis of the degradation behaviors indicates a bright future of this system in outer space applications. Notably, the use of polymer acceptor as a dual function additive in the other four photovoltaic systems was also confirmed, demonstrating the good generality of this polymer-doping strategy.

This article analyzes and discusses a multi-objective optimization-based layer-by-layer blade-coating approach, which provides a new technology choice for large-scale manufacturing of organic solar cells.