One key issue in characterization of organic solar cells with solution processed interfacial layers

Area of Science:

• Materials Science
• Organic Electronics
• Photovoltaics

Background:

• Solution-processed interfacial layers are crucial for efficient charge collection in bulk heterojunction organic solar cells (OSCs).
• The preparation method of these interfacial layers significantly influences device performance metrics such as power conversion efficiency (PCE), short-circuit current density (JSC), and fill factor (FF).

Purpose of the Study:

• To investigate the impact of static (S-PDIN) and dynamic (D-PDIN) spin coating methods on the performance of PDIN interfacial layers in OSCs.
• To analyze the correlation between interfacial layer preparation, charge collection, and overall device efficiency.
• To establish the importance of balanced JSC and FF for efficient OSCs and the necessity of shadow masks for accurate J-V measurements.

Main Methods:

• Preparation of PDIN interfacial layers using static spin coating (S-PDIN) and dynamic spin coating (D-PDIN) from a PDIN methanol solution.
• Fabrication and characterization of bulk heterojunction organic solar cells (OSCs) incorporating these interfacial layers.
• Current density versus voltage (J-V) measurements with and without a shadow mask to evaluate device performance (PCE, JSC, FF).

Main Results:

• OSCs with S-PDIN layers showed a PCE of 13.88% with a high JSC (26.45 mA cm⁻²) but a low FF (58.94%) without a shadow mask.
• OSCs with D-PDIN layers achieved a PCE of 12.56% with a lower JSC (18.85 mA cm⁻²) but a higher FF (74.88%).
• With a shadow mask, both S-PDIN and D-PDIN OSCs exhibited FFs over 77% and similar JSC and PCE values, suggesting the S-PDIN layer may enhance PEDOT:PSS conductivity.

Conclusions:

• The spin coating method critically affects the performance of solution-processed interfacial layers in OSCs, influencing the balance between JSC and FF.
• Accurate evaluation of OSCs with solution-processed interfacial layers necessitates the use of a shadow mask during J-V measurements.
• Achieving a well-balanced JSC and FF is a key indicator for developing highly efficient organic solar cells.