Thick Active-Layer Organic Solar Cells

Organic solar cells(OSCs)present a promising renewable energy technology due to their cost-effectiveness,adaptability,and lightweight nature.The advent of non-fullerene acceptors has further boosted their significance,allowing for power conversion efficiencies surpassing 19%even with an active layer thickness of about 100 nm.However,in order to achieve large scale production,it is necessary to fabricate OSCs with thicker active layers exceeding 300 nm that are compatible with large-area printing techniques.Nevertheless,OSCs with thick active layers have inferior performance compared to those with thin active layers.To expedite the transition of OSCs from laboratory to industrial high-throughput manufacturing,considerable efforts have been made to comprehend the performance limitations of thick active-layer OSCs,develop novel photoactive materials that are high-performance and tolerant towards the thickness of the active layer,and optimize the morphology of the photoactive layer and device structure.This review aims to provide a comprehensive summary of the mechanisms that lead to efficiency loss in thick active-layer OSCs,the representative works on molecular design,and the optimization strategies for high-performance thick active-layer OSCs,and the remaining challenges that must be addressed.

A ternary organic solar cell with 300 nm thick active layer shows over 14% efficiency

In order to meet the requirements for making organic solar cells(OSCs)through solution printing techniques,great efforts have been devoted into developing high performance OSCs with relatively thicker active layers.In this work,a thick-film(300 nm)ternary OSC with a power conversion efficiency of 14.3%is fabricated by introducing phenyl-C61-butyric-acid-methyl ester(PC61BM)into a PBDB-T-2Cl:BTP-4 F host blend.The addition of PC61BM is found to be helpful for improving the hole and electron mobilities,and thus facilitates charge transport as well as suppresses charge recombination in the active layers,leading to the improved efficiencies of OSCs with relatively thicker active layers.Our results demonstrate the feasibility of employing fullerene derivative PC61BM to construct a high-efficiency thick-film ternary device,which would promote the development of thick layer ternary OSCs to fulfill the requirements of future roll to roll production.