Enhanced photovoltaic properties by device optimization of benzotriazole-containing conjugated polymers

ABSTRACT

We prepared three D-π-A conjugated polymers consisting of a benzotriazole building block as an acceptor. Carbazole, fluorene, and benzodithiophene units were utilized for electron donors in the conjugated backbones to form PBTZCZ, PBTZFL, and PBTZSP, respectively. Their structural, thermal, optical, and photovoltaic properties were investigated. After optimizing device processing conditions for conventional bulk-heterojunction solar cells, we could achieve a highest PCE of 2.43% with J_sc of 6.58 mA/cm², V_oc of 0.74 V, and FF of 49.2% for PBTZCZ:PC₆₀BM. Further improvement could be accomplished by inverted solar cell devices showing the PCE of 3.81% with J_sc of 7.69 mA/cm², V_oc of 0.88 V, and FF of 55.9%.

KEYWORDS:

• Benzotriazole building blocks
• D-π-A conjugated polymers
• bulk-heterojunction solar cells
• inverted solar cell
• photovoltaics

Funding

This work was supported by The Leading Human Resource Training Program of Regional Neo industry through the NRF funded by the Ministry of Science, ICT and future Planning (2016H1D5A1911217) and Basic Science Research Program (2015R1D1A1A01061460).