Direct Evaluation of Intrinsic Optoelectronic Performance of Organic Photovoltaic Cells with Minimizing Impurity and Degradation Effects

Abstract

A correlation between the photovoltaic performance and dynamics of transient photoconductivity is investigated by fl ash-photolysis time-resolved microwave conductivity (FP-TRMC). This electrode-less technique offers chances to mitigate barriers for direct, speedy, and robust evaluation of bulk heterojunction (BHJ) fi lm. We examined the blend ratio, process (solvent and thermal annealing), and impurity (a metal complex of Pd) and degradation effects in BHJ fi lms consisting of poly(3-hexylthiophene) (P3HT) and methanofullerene (PCBM). The minimum charge carrier mobility of 0.22 cm 2 V − 1 s − 1 was found in P3HT:PCBM = 1:1 fi lm along with 3.26% power conversion effi ciency. The revealed good correlation is not only applicable to process optimization, but also expected as a facile screening method to survey the potential of optoelectronic materials.

The isotopic effects of deuteration on optoelectronic properties of conducting polymers

“…Several studies have previously demonstrated that P3HT molecular weight variations in the range of 10-20 kg mol À 1 do not significantly affect the morphology and device performance of the pristine polymer or P3HT/PCBM-based photovoltaics [22][23][24] . In addition, the Ni residues in the highly pure protonated and deuterated P3HT polymers synthesized for this study were measured by inductively coupled plasma mass spectroscopy to be less than 0.0014 wt.%, which is 50 times smaller than the threshold concentration of metal impurities for noticeable effects on device performance in previous studies [25][26][27] . Therefore, we exclude the impact of the molecular weight difference and metal residues on the measured optoelectronic properties between the deuterated and protonated P3HT polymers in this work.…”

Study of Photoelectric Conversion in Benzotrithiophene-Based Conjugated Semiconducting Polymers

“…This is assumed due to an essential role of electron delocalization in PCBM aggregates for efficient charge separation. In the case of crystalline polymers such as poly(3-hexylthiophene) 33,34) and high performing LBPs, 35) the 1:1 blend ratio (50 wt%) is often optimal, because self-assembling nature of polymer concurrently promotes the growth of PCBM aggregates. In the present case, BTT-TP is amorphous, while BTT-FT and BTT-NTz are more crystalline, as evidenced by X-ray diffraction (vide infra).…”

Exploring Photovoltaic Feasibility of Pentaaryl [60]Fullerene in Bulk Heterojunction Architecture

“…C 60 has a very weak fluorescence at ca. 700 nm, 32) as a result of symmetrically forbidden transition from the excited singlet state to ground state.…”