11.6 % Efficient textured InP solar cell with Nb2O5: A cutting-edge electron transport layer innovation

Abstract

Enhancing the efficiency of solar cells depends on minimizing reflection losses to boost photon absorption. In this study, we investigated the chemical etching process of pristine InP(100), (named as pris-InP(100)). Our findings demonstrate that the etching process resulted in a self-organizing V-groove microstructure, as revealed by atomic force microscopy and scanning electron microscopy. This induced V-groove microstructure resulted a significant reduction in the reflection loss. Through temporal variation in the etching process, we identified that a 5-minute etch (named as etch5-InP(100)), yielded the lowest reflectance. Additionally, radiofrequency (RF) magnetron sputtering was employed to deposit a 10 nm Nb₂O₅ thin film on both pris-InP (100) and etch5-InP (100) samples. The results indicated that the thin film on etch5-InP(100) exhibited significantly lower reflectance compared to pris-InP(100). Moreover, ab-initio calculations verified the stability and presence of native oxide at the interface of the Nb₂O₅/InP(100) heterostructure. Furthermore, dark current-voltage (I-V) characteristics indicated typical diode behaviour for both Nb₂O₅ thin films deposited on pris-InP(100) and etch5-InP(100). Notably, light I-V measurements revealed that the Nb₂O₅ thin film on etch5-InP(100) achieved a higher efficiency of 11.6 % compared to the 8.7 % efficiency of pris-InP(100). This study provides valuable insights and guidelines for the development of high-efficiency InP-based solar cells.