Effects of front InGaP layer thickness on solar cell characteristics in InP/InGaP quantum dot solar cells

Abstract

To investigate the impact of the front InGaP layer thickness on solar cell characteristics in InGaP-based InP quantum dot (QD) solar cells, we prepared InP/InGaP QD solar cells with a front i-InGaP layer and compared their performance with those of a device without i-InGaP layer and InGaP solar cell. Even though the QD solar cells show open-circuit voltage (Voc) reduction compared to the InGaP solar cell, the device with thin i-InGaP layer shows slightly higher Voc compared to the device with no i-InGaP layer. This result is explained by the fact that the saturation current in dark current characteristics decreases in the device with thin i-InGaP layer. This likely originates from the suppressed thermal carrier escape from QDs. Our findings reveal that the i-InGaP layer in the QDs significantly affects the photovoltaic performance. For further improvement of photovoltaic performance of such devices, optimization of the i-InGaP layer thickness is necessary.