<p>Commercialization of Organic photovoltaic (OPV) devices based on P3HT:PCBM bulk heterojunctions (BHJs) are limited by morphological instability and loss in their power conversion efficiency (PCE) over time. These instabilities arise from the inherent tendency of PCBM molecules to agglomerate, leading to phase separation and reduced donor-acceptor interfacial area. In this work, we review strategies to suppress such degradation mechanisms and enhance device stability. Two key approaches are examined: (i) promoting physical encapsulation of PCBM molecules by coiled P3HT chains through controlled spin-coating rates, and (ii) replacement of <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\mathrm{PC_{60}BM}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">PC</mi> <mn>60</mn> </msub> <mi mathvariant="normal">BM</mi> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\mathrm{PC_{70}BM}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">PC</mi> <mn>70</mn> </msub> <mi mathvariant="normal">BM</mi> </mrow> </math></EquationSource> </InlineEquation> to inhibit dimerization due to its ellipsoidal geometry and higher molecular mass. Experimental results show that low spin speeds improve polymer chain entanglement, suppressing PCBM diffusion and slows PCE decay. Additionally, devices incorporating <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$\mathrm{PC_{70}BM}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">PC</mi> <mn>70</mn> </msub> <mi mathvariant="normal">BM</mi> </mrow> </math></EquationSource> </InlineEquation> exhibit delayed degradation compared to <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$\mathrm{PC_{60}BM}$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi mathvariant="normal">PC</mi> <mn>60</mn> </msub> <mi mathvariant="normal">BM</mi> </mrow> </math></EquationSource> </InlineEquation> based cells. Finally, we highlight a molecular engineering approach using dihydroxypyridine (DHP) to create intermolecular binding between donor and acceptor phases. These strategies collectively offer a pathway to enhance both morphological and operational stability in P3HT:PCBM-based solar cells.</p>

Enhancing the morphological and operational stability of P3HT:PCBM bulk heterojunction solar cells: current understanding

期刊论文
发表日期：

2026年2月14日

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Inderpreet Singh,
Kuldeep Kumar,
P. Arun

摘要

Commercialization of Organic photovoltaic (OPV) devices based on P3HT:PCBM bulk heterojunctions (BHJs) are limited by morphological instability and loss in their power conversion efficiency (PCE) over time. These instabilities arise from the inherent tendency of PCBM molecules to agglomerate, leading to phase separation and reduced donor-acceptor interfacial area. In this work, we review strategies to suppress such degradation mechanisms and enhance device stability. Two key approaches are examined: (i) promoting physical encapsulation of PCBM molecules by coiled P3HT chains through controlled spin-coating rates, and (ii) replacement of $\mathrm{PC_{60}BM}$ ${PC}_{60} BM$ with $\mathrm{PC_{70}BM}$ ${PC}_{70} BM$ to inhibit dimerization due to its ellipsoidal geometry and higher molecular mass. Experimental results show that low spin speeds improve polymer chain entanglement, suppressing PCBM diffusion and slows PCE decay. Additionally, devices incorporating $\mathrm{PC_{70}BM}$ ${PC}_{70} BM$ exhibit delayed degradation compared to $\mathrm{PC_{60}BM}$ ${PC}_{60} BM$ based cells. Finally, we highlight a molecular engineering approach using dihydroxypyridine (DHP) to create intermolecular binding between donor and acceptor phases. These strategies collectively offer a pathway to enhance both morphological and operational stability in P3HT:PCBM-based solar cells.