Efficiency boost of inverted polymer solar cells using electrodeposited n-type Cu2O electrons selective transport layers (ESTLs)

Polymer solar cells (PSCs) have attracted tremendous interest as suitable candidates for harnessing solar energy in the recent years. The inherent optoelectronic properties of the inorganic transition metal oxide, negative type cuprous oxide (n-Cu2O), makes it an attractive candidate to improve the performance of PSCs when incorporated as the electron selective transport layers (ESTLs) in the device. In this study, inverted PSCs were fabricated on stainless steel (SS) substrates with n-Cu2O as the ESTL. The n-Cu2O films were prepared by electrodeposition method, followed by annealing under ambient conditions. The active layer material was prepared as bulk heterojunction blend using regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM). Poly-(4,3-ethylene dioxythiophene):poly(styrenesulphonate) (PEDOT:PSS) was used as the hole transport layer (HTL) and the final device structure was SS/n-Cu2O/P3HT:PCBM/PEDOT:PSS/Au. Annealing of the n-Cu2O ESTL in air was optimized observing the photoactive performance of the device. Optoelectronic performance of the devices was characterized using spectral response and dark and light current-voltage (I-V) measurements. n-Cu2O ESTL- incorporated devices have absorbed more photons in the short wavelength region of 450.600 nm with the annealing of n-Cu2O ESTL due to the reduction of electron-hole recombination. The performance of the devices was significantly increased after incorporating pre-annealed n-Cu2O ESTL at 175 degrees C for 30 min in air. The maximum power conversion efficiency (PCE) was 0.35%.

Automated summary

Polymer solar cells (PSCs) have gained significant interest as potential candidates for solar energy conversion. In this study, the inorganic transition metal oxide, negative type cuprous oxide (n-Cu2O), was used as the electron selective transport layer (ESTL) to enhance the performance of PSCs. The devices were fabricated on stainless steel (SS) substrates with an inverted structure, and the optoelectronic performance was characterized using spectral response and dark and light current-voltage (I-V) measurements. It was found that annealing the n-Cu2O ESTL improved the photon absorption in the short wavelength region, resulting in a significant increase in the device performance.