Self Doping of the Transport Layers Decreases the Bimolecular Recombination by Reducing Static Disorder

Electron transport layers ETLs have a crucial role in the solar cells performance. Generally, ETLs are characterized in terms of the interface properties and conductivity rather than their effect on the photoactive layer. Herein, two ETLs, 2,9 bis 3 3 dimethylamino propyl amino propyl anthra[2,1,9 def 6,5,10 d amp; 8242;e amp; 8242;f amp; 8242;]diisoquinoline 1,3,8,10 2H,9H tetraone PDINN and 2,9 bis[3 dimethyloxidoamino propyl]anthra[2,1,9 def 6,5,10 d amp; 8242;e amp; 8242;f amp; 8242;]diisoquinoline 1,3,8,10 2H,9H tetrone, are compared in the conventional PM6 Y6 organic solar cell OSC structure and the influence of the ETL on the photoactive layer is shown. It is shown that a significant portion of the unpaired electrons of PDINN is mobile by combining electron paramagnetic resonance and Hall effect measurements. It is established that the high doping in PDINN ETL changes the dark electron concentration of the photoactive layer. The impacts of this change in the photoactive layer can be observed in the reduced static energetic disorder, and subsequently in the nonradiative recombination of free carriers. The results can be used to suppress nonradiative recombination in OSC, which can significantly boost their efficiency