Thermal Stabilisation of Polymer–Fullerene Bulk Heterojunction Morphology for Efficient Photovoltaic Solar Cells

Abstract

A novel stable bisazide molecule that can freeze the bulk heterojunction morphology at its optimized layout by specifically bonding to fullerenes is reported. The concept is demonstrated with various polymers: fullerene derivatives systems enable highly thermally stable polymer solar cells.

Enhanced thermal stability of organic solar cells comprising ternary D-D-A bulk-heterojunctions

“…13 Such third components can be crosslinkers, [14][15][16] In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers. After thermal stress at 120°C for 2 h, the corresponding solar cells maintain over 90% of their initial performance.…”

“…12 Another promising concept to reduce degradation in fullerene-based solar cells is the use of third components which can improve the mechanical, photo, air and thermal stability of organic solar cells. 13 Such third components can be crosslinkers, [14][15][16] conventional fullerenes, [17][18][19] modified fullerene derivatives, [20][21][22] compatibilizers 23,24 or insulating polymers. 25 In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers.…”

“…6,7 Upon thermal stress, one of the major degradation mechanisms is the aggregation of fullerene acceptors, commonly [6,6]-phenyl C 71 -butyric acid methyl ester (PC 71 BM) or [6,6]-phenyl C 61 -butyric acid methyl ester (PC 61 BM). 8,9 In the recent literature, several methods were discussed to hamper fullerene aggregation-for example sample irradiation during annealing, 10 structural modification of fullerenes 11 or replacing fullerenes with non-fullerene acceptors.12 Another promising concept to reduce degradation in fullerene-based solar cells is the use of third components which can improve the mechanical, photo, air and thermal stability of organic solar cells.13 Such third components can be crosslinkers, [14][15][16] In this work, we overcome the aggregation of the fullerene acceptor PC 61 BM during thermal annealing by employing ternary D-D-A blends comprising two commercially available donor polymers. After thermal stress at 120°C for 2 h, the corresponding solar cells maintain over 90% of their initial performance.…”

Dual Function Additives: A Small Molecule Crosslinker for Enhanced Efficiency and Stability in Organic Solar Cells

“…[ 14 ] Azides, for example, have been traditionally used in photoresists to produce nitrenes, inserting into C=C bonds in, for example, isoprene resin, emitting only inert nitrogen gas. More recently, sterically hindered fl uorophenyl azides (sFPA's) have also been demonstrated to be directed to insert selectively into C-H bonds in the alkyl side-chains of a conjugated polymer backbone.…”

Perspective of a new trend in organic photovoltaic: ternary blend polymer solar cells

“…acceptor material. However, in the most widely used binary blend systems, the electron acceptor (PCBM) tends to aggregate into big clusters, which destroys the morphology of the active layer and reduces the PCE drastically [24,25]. The added third component can be designed to achieve better morphology compared to the reference devices.…”