Single Junction Inverted Polymer Solar Cell Reaching Power Conversion Efficiency 10.31% by Employing Dual-Doped Zinc Oxide Nano-Film as Cathode Interlayer

Abstract

We present high efficiency and stable inverted PSCs (i-PSC) by employing sol-gel processed simultaneously doped ZnO by Indium and fullerene derivative (BisNPC60-OH) (denoted as InZnO-BisC60) film as cathode interlayer and PTB7-Th:PC71BM as the active layer (where PTB7-Th is a low bandgap polymer we proposed previously). This dual-doped ZnO, InZnO-BisC60, film shows dual and opposite gradient dopant concentration profiles, being rich in fullerene derivative at the cathode surface in contact with active layer and rich in In at the cathode surface in contact with the ITO surface. Such doping in ZnO not only gives improved surface conductivity by a factor of 270 (from 0.015 to 4.06 S cm−1) but also provides enhanced electron mobility by a factor of 132 (from 8.25*10−5 to 1.09*10−2 cm2 V−1 s−1). The resulting i-PSC exhibits the improved PCE 10.31% relative to that with ZnO without doping 8.25%. This PCE 10.31% is the best result among the reported values so far for single junction PSC.

Interfacial Materials for Organic Solar Cells: Recent Advances and Perspectives

“…Thus all these factors should be systemically evaluated for balancing the interfacial/optoelectronic properties of ternary oxide CILs when fabricating OPV devices. Incorporating the optimized ternary oxides as CILs, better performance of OSCs were observed for all the AZO, IZO, GZO, and ZTO CILs because of their reduced recombination at the interfaces, improved electron‐transport/hole‐blocking properties with respect to the standard ZnO CILs 26, 104, 106, 109. For example, the In doping in ZnO improved the surface conductivity by a factor of 567 (from 0.015 to 8.51 S cm −1 ) and enhanced electron mobility in the vertical direction by a factor of 115 (from 8.25 × 10 −5 to 9.51 × 10 −3 cm 2 V −1 s −1 ) 26.…”

“…Incorporating the optimized ternary oxides as CILs, better performance of OSCs were observed for all the AZO, IZO, GZO, and ZTO CILs because of their reduced recombination at the interfaces, improved electron‐transport/hole‐blocking properties with respect to the standard ZnO CILs 26, 104, 106, 109. For example, the In doping in ZnO improved the surface conductivity by a factor of 567 (from 0.015 to 8.51 S cm −1 ) and enhanced electron mobility in the vertical direction by a factor of 115 (from 8.25 × 10 −5 to 9.51 × 10 −3 cm 2 V −1 s −1 ) 26. The resultant inverted OSCs (PTB7‐Th:PC 71 BM) using the IZO CIL exhibited an improved PCE of 9.11% in relative to the devices with ZnO (PCE = 8.25%).…”

“…For example, high PCEs of 9–10% for single‐junction OSCs are achieved by combining [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC 71 BM) as an acceptor with a low‐bandgap polymer, poly({4,8‐bis[(2‐ethylhexyl)oxy]benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl}{3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl] thieno[3,4‐b]thiophenediyl}) (PTB7) or its derivative PTB7‐Th (poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐ b :4,5‐ b ′]dithiophene‐ co ‐3‐fluorothieno[3,4‐ b ]thiophene‐2‐carboxylate]) as a donor in the active layer 23, 24, 25, 26, 27. Recently, Yan and co‐workers reported a PCE of 10.8% from inverted single‐junction cells based on a new polymer:fullerene (PffBT4T‐2OD:PC 71 BM) system by controlling the aggregation and morphology of the active layer 28.…”

A Tetraperylene Diimides Based 3D Nonfullerene Acceptor for Efficient Organic Photovoltaics

“…Fullerene derivatives with unique phase and multidimensional charge‐transporting capabilities have played a central role as electron acceptor in BHJ devices leading to ≈11% power conversion efficiency (PCE) 1, 2. In spite of the widespread usage of fullerene acceptors, they do suffer from drawbacks including weak absorption of visible light, poor chemical and electronic tunability, and high production cost.…”

Light Manipulation in Organic Photovoltaics

“…Starting from the pioneered bilayer heterojunction OPV,5 much effort has been made toward improving the power conversion efficiency (PCE) of both small molecule and polymer based cells 6, 7, 8, 9, 10, 11, 12. Sophisticated strategies like absorber bandgap tailoring, morphology control, and interface engineering have recently been developed, pushing the PCEs over 13% and 11% for tandem‐ and single‐junction OPVs, respectively 3, 9, 10, 13, 14, 15, 16, 17, 18, 19, 20. It is expected that the PCEs of OPVs will make a remarkable progress towards a competitive level of industrialization of >15%.…”