Reduced Nonradiative Voltage Loss in Terpolymer Solar Cells

• The dissociation of hybrid local exciton and charge transfer excitons (LE-CT) in efficient bulk-heterojunction nonfullerene solar cells contributes to reduced nonradiative photovoltage loss, a mechanism that still remains unclear. Herein we studied the energetic and entropic contribution in the hybrid LE-CT exciton dissociation in devices based on a conjugated terpolymer. Compared with reference devices based on ternary blends, the terpolymer devices demonstrated a significant reduction in the nonradiative photovoltage loss, regardless of the acceptor molecule, be it fullerene or nonfullerene. Fourier transform photocurrent spectroscopy revealed a significant LE-CT character in the terpolymer-based solar cells. Temperature-dependent hole mobility and photovoltage confirm that entropic and energetic effects contribute to the efficient LE-CT dissociation. The energetic disorder value measured in the fullerene- or nonfullerene-based terpolymer devices suggested that this entropic contribution came from the terpolymer, a signature of higher disorder in copolymers with multiple aromatic groups. This gives new insight into the fundamental physics of efficient LE-CT exciton dissociation with smaller nonradiative recombination loss.

Subject headings

NATURVETENSKAP  -- Fysik -- Annan fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Other Physics Topics (hsv//eng)

NATURVETENSKAP  -- Kemi -- Annan kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Other Chemistry Topics (hsv//eng)

NATURVETENSKAP  -- Fysik -- Den kondenserade materiens fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences -- Condensed Matter Physics (hsv//eng)

Publication and Content Type

art (subject category)

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