A Polymer/Carbon‐Nanotube Ink as a Boron‐Dopant/Inorganic‐Passivation Free Carrier Selective Contact for Silicon Solar Cells with over 21% Efficiency

Abstract

Traditional silicon solar cells extract holes and achieve interface passivation with the use of a boron dopant and dielectric thin films such as silicon oxide or hydrogenated amorphous silicon. Without these two key components, few technologies have realized power conversion efficiencies above 20%. Here, a carbon nanotube ink is spin coated directly onto a silicon wafer to serve simultaneously as a hole extraction layer, but also to passivate interfacial defects. This enables a low‐cost fabrication process that is absent of vacuum equipment and high‐temperatures. Power conversion efficiencies of 21.4% on an device area of 4.8 cm2 and 20% on an industrial size (245.71 cm2) wafer are obtained. Additionally, the high quality of this passivated carrier selective contact affords a fill factor of 82%, which is a record for silicon solar cells with dopant‐free contacts. The combination of low‐dimensional materials with an organic passivation is a new strategy to high performance photovoltaics.

Endohedral Filling Effects in Sorted and Polymer-Wrapped Single-Wall Carbon Nanotubes

“…After studying uniformly filled SWCNTs we turn to the situation faced by most researchers, , namely, using PFO-BPy to disperse and sort SWCNTs from a commercially available raw soot. In this case the endohedral state is mostly unknown (at least it is not stated by the manufacturer) and is variable.…”

FeCl3-functionalized graphene oxide/single-wall carbon nanotube/silicon heterojunction solar cells with an efficiency of 17.5%

“…As a result several methods, including SWCNT film doping, the introduction of antireflection layers, and device structure optimization have been developed to improve the power conversion efficiency (PCE) of these cells. 1,11–14 For example, combining a SWCNT film with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), 15 Nafion, 12,16–18 or MoOx 1 has proved effective in improving both the carrier transfer and light absorption.…”

Utilization of Multifunctional Environment‐Friendly Organic Dopants Inspired from Nature for Carbon Nanotube‐Based Planar Heterojunction Silicon Solar Cells

“…In addition, TFMS is a superacid with a pK a value of -14.7 and therefore extremely corrosive beyond measure. [17,18] Relatively safer polymer-based acid dopants, namely, Nafion, [19][20][21] poly(acrylic acid) (PAA), [22] and poly(styrene sulfonate) (PSS), [23] have been reported. However, the synthesis of these polymeric acids is a costly process and causes environmental pollution because the synthesis involves the use of toxic organic solvents.…”