Effects of incorporation of copper sulfide nanocrystals on the performance of P3HT: PCBM based inverted solar cells

• Cu2S nanocrystals (NCs) have been synthesized and incorporated into the photoactive layer of P3HT: PCBM.
• The efficiency and charge carrier mobility have been increased in Cu2S embedded devices.
• Addition of Cu2S NCs facilitates the intramolecular charge transfer from P3HT to PCBM through Cu2S NCs.
• The efficiency in Cu2s NCs embedded devices is more than 100% increase in comparison with devices without Cu2S NCs.
• Decrease in the effective lifetime has been found after incorporation of Cu2S NCs in P3HT: PCBM matrix.

It has been reported that performance of bulk heterojunction organic solar cells can be improved by incorporation of an additive like metal and semiconducting nanoparticles in the active layer. Here in, we have synthesized Cu2S nanocrystals (NCs) by chemical route and studied its dispersion in poly (3-hexylthiophene) [6, 6]-phenyl C61-butyric acid methyl ester (P3HT: PCBM) matrix. Variation in the performance parameters with change in the concentration of Cu2S NCs into the P3HT: PCBM matrix has also been studied and it was found that the inverted geometry device with concentration of 20 wt% of Cu2S NCs and having the structure ITO/ZnO (NPs)/P3HT: PCBM:Cu2S NCs/MoO3/Al has shown maximum efficiency of 3.39% which is more than 100% increase in comparison with devices without Cu2S NCs. Photoluminescence measurements studies unveiled that the incorporation of Cu2S NCs into a P3HT: PCBM matrix has helped in quenching photoluminescence which suggests more effective exciton dissociation at the interfaces between the P3HT and PCBM domains. The Nyquist plots obtained from impedance spectroscopy at 1 V bias in the dark has suggested the effective lifetime and global mobilities for P3HT: PCBM as 0.267 ms and 1.17 × 10−3 cm2/V-S and for P3HT: PCBM:Cu2S NCs (20 wt%) systems as 0.156 ms and 2.02 × 10−3 cm2/V-S respectively. Based on observed photoluminescence quenching, calculated effective lifetime and global mobility, we have tried to explain the possible reason for improvement in the efficiency with the very well dispersion of Cu2S NCs into the P3HT: PCBM matrix.

Copper sulfide nanocrystals (Cu2S NCs) have been successfully synthesized and incorporated into the photoactive layer of P3HT: PCBM bulk heterojunction to enhance the power conversion efficiency and charge carrier mobility for fabrication of organic solar cells.Figure optionsDownload as PowerPoint slide