Solution‐Processed Tin Oxide‐PEDOT:PSS Interconnecting Layers for Efficient Inverted and Conventional Tandem Polymer Solar Cells

Abstract

Tin oxide nanoparticles are employed as an electron transporting layer in solution‐processed polymer solar cells. Tin oxide based devices yield excellent performance and can interchangeably be used in conventional and inverted device configurations. In combination with poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as a hole transporting layer, tin oxide forms an effective interconnecting layer (ICL) for tandem solar cells. Conventional and inverted tandem cells with this ICL provide efficiencies up to 10.4% in good agreement with optical‐electrical modeling simulations. The critical advantage of tin oxide in an ICL in a conventional tandem structure over the commonly used zinc oxide is that the latter requires the use of a pH‐neutral formulation of PEDOT:PSS to fabricate the ICL, limiting the open‐circuit voltage (VOC) because of its low work function. The SnO2/PEDOT:PSS ICL, on the other hand, provides a nearly loss‐free VOC.

Recent Advances of Synthesis, Properties, Film Fabrication Methods, Modifications of Poly(3,4‐ethylenedioxythiophene), and Applications in Solution‐Processed Photovoltaics

“…[277] Later on, other ICLs of TiO X /PEDOT:PSS and SnO 2 /PEDOT:PSS have also been explored. [278,279] Recently, the optimized PEDOT:PSS/ZnO ICLs have achieved the highest PCE of 17.3% for inverted tandem OSCs (Figure 18e). [274] Such ICLs have also displayed well compatibility for fully printed tandem OSCs.…”

Recent Advances Toward Highly Efficient Tandem Organic Solar Cells

“…In tandem OSCs, DPP-based polymers were always used in the top subcells to harvest low-energy photons. Quite a few research work was based on multithiophene and DPP blocks, such as poly[ (2,5- [73,74] [75][76][77][78] poly [3,6- [79] [80]…”

“…poly (3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS)/metal oxide is the most used ICL in tandem OSCs. The n-type metal oxide nanoparticles, such as zinc oxide (ZnO), [81,82,206] titanium dioxide (TiO 2 ), [33,140,154,207] and tin oxide (SnO 2 ), [77] are prepared by hydrothermal methods and dispersed in polar organic solvents. The surface defects of ZnO and aluminum-doped ZnO (AZO) can be modified by self-assembled monolayer (C 60 -SAM) with anchoring groups, [155] and polymer electrolytes of poly(9,9 0 -bis(6 00 -N,N,N-trimethylammoniumhexyl) fluorene-co-alt-phenylene) dibromide (FPQ-Br), [89] polyethylenimine (PEI), [69,115] partially ethoxylated polyethylenimine (PEIE), [108,138,164] etc.…”

“…[33] To circumvent that, the pH neutral PEDOT:PSS analogues of m-PEDOT:PSS and highly conductive poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PH100) with high viscosity were used. [21,33,[38][39][40]58,70,[75][76][77]85,97,99,102,122,[127][128][129]132,138,144,164,208] Zhou and coworkers found that PEDOT:PSS with surfactant deposited on top of nonfullerene-based tandem OSCs might lead to chemical reaction between PEDOT:PSS and the NFA (IT-4F), which would be detrimental to the device performance. [100] To avoid the direct deposition of PEDOT:PSS on top of the active layer, they introduced a hydrogen molybdenum bronze (H x MoO 3 ) layer between the bottom active layer and PEDOT: PSS.…”

“…In tandem OSCs, DPP‐based polymers were always used in the top subcells to harvest low‐energy photons. Quite a few research work was based on multithiophene and DPP blocks, such as poly[(2,5‐bis(2‐hexyldecyl)‐2,3,5,6‐tetrahydro‐3,6‐dioxopyrrolo[3,4‐c]pyrrole‐1,4‐diyl)‐alt‐([2,2′:5′,2″‐terthiophene]‐5,5″‐diyl)] (PDPP3T), [ 73,74 ] poly[(2,5‐bis(2‐hexyldecyl‐2,3,5,6‐tetrahydro‐3,6‐dioxopyrrolo[3,4‐c]pyrrole‐1,4‐diyl)‐alt‐(3′,3″‐dimethyl‐2,2′:5′,2″‐terthiophene]‐5,5″‐diyl)] (PMDPP3T), [ 75–78 ] poly[3,6‐bis(4′‐dodecyl‐[2,2′]bithiophenyl‐5‐yl)‐2,5‐bis(2‐ethylhexyl)‐2,5‐dihydropyrrolo[3,4‐]pyrrole‐1,4‐dione] (pBBTDPP2), [ 79 ] poly[(2,5‐bis(2‐decyltetradecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐3,6‐diyl)‐alt‐(2,2′:5′,2″:5″,2‴‐quaterthiophene‐5,5‴‐diyl)] (PDPP4T), [ 80 ] poly[(2,5‐bis(2‐hexyldecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐3,6‐diyl)‐alt‐(3‴,4′‐didodecyl‐2,2′:5′,2″:5″,2‴:5‴,2‴′‐quinquethiophene‐5,5‴′‐diyl)] (PDDP5T), [ 40,81 ] poly[(2,5‐bis(2‐hexyldecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐3,6‐diyl)‐alt‐(3‴,4′‐dihexyl‐2,2′:5′,2″:5″,2‴:5‴,2‴′‐quinquethiophene‐5,5‴′‐diyl)] (pDPP5T‐2), [ 41,82–84 ] poly[(2,5‐bis(2‐hexyldecyl)‐pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐3,6‐diyl)‐alt‐(bis(thiopen‐2‐yl)thieno[3,2‐b]thiophene‐2,5‐diyl)] (DT‐PDPP2T‐TT), [ 85 ] and so on. These polymers exhibited a wide absorption range even near 1000 nm.…”