Design of Ultrathin InP Solar Cell Using Carrier Selective Contacts

Abstract

Most recently, III-V based ultra-thin solar cells have attracted much attention for their inherent advantages such as increased tolerance to defect recombination, efficient charge carrier separation, photon recycling, flexibility, and reduced material consumption. However, so far, almost all reported devices make use of conventional doped p-i-n kind of structures with a wide bandgap III-V lattice-matched epitaxial window layer, for passivation and reduced contact recombination. Here, we show that a high-efficiency device can be obtained utilizing an InP thin film of thickness as low as 280 nm, without the requirement of a conventional p-n homojunction or epitaxial window layer. This is achieved by utilizing a wide bandgap electron and hole selective contacts for electrons and holes transport, respectively. Under ideal conditions (assuming Interface Recombination Velocity (IRV) = 10 3 cm/s and bulk lifetime =1 us), the proposed solar cell structure can achieve efficiency as high as 28%. Although, in the presence of bulk and interface SRH recombination, the efficiency reduces, still for bulk minority carrier lifetime as low as 2ns and an IRV as high as 10 5 cm/s, an efficiency of ~22% can be achieved with InP thickness as low as 280 nm. The proposed device structure will be beneficial in cases where the growth of controlled p-n homojunction and window layer can be tedious as in case of low-cost deposition techniques, such as thin-film vapour-liquidsolid (TF-VLS) and close-spaced vapour transport (CSVT).

Photon Recycling in Semiconductor Thin Films and Devices

“…[31,37,38,45,66,92,93,140,[154][155][156][157] Nowadays, PR plays an important role in improving the limit efficiencies of III-V materials solar cells. [38,59,64,71,[158][159][160][161][162][163][164][165][166][167][168][169][170][171][172] At the beginning, a lot of research studied the effect of PR in III-V materials solar cells through theoretical calculations. In 1994, Durbin and Gray showed the J-V characteristics of the thin GaAs solar cells under illumination (500 Suns, AM 1.5 direct) both with and without PR in Figure 12a.…”

“…As expected, PR improved the V oc from 1.05 to 1.12 V, while maintaining the J sc and fill factor (FF) at 28.2 mA cm −2 and 88.3%, respectively. [160] As for how to achieve PR in III-V materials solar cells, for example, Gruginskie et al reported that the performance of thinfilm GaAs solar cells was increased by PR using a rear mirror. [59] Particularly, the total reflectance at the back of the solar cell in this case was increased from 63.5% to 93.2%.…”

“…To date, PR has been applied in crystalline silicon solar cells, [ 13 , 14 , 15 , 16 , 68 , 147 , 148 , 149 , 150 , 151 , 152 , 153 ] III‐V materials solar cells, [ 31 , 37 , 38 , 45 , 59 , 64 , 66 , 71 , 92 , 93 , 140 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 ] organic solar cells [ 175 , 176 ] and perovskite solar cells. [ 28 , 29 , 87 , 95 , 111 , 177 , 178 ,…”

“…[ 31 , 37 , 38 , 45 , 66 , 92 , 93 , 140 , 154 , 155 , 156 , 157 ] Nowadays, PR plays an important role in improving the limit efficiencies of III–V materials solar cells. [ 38 , 59 , 64 , 71 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 , 168 , 169 , 170 , 171 , 172 ]…”

“…As expected, PR improved the V oc from 1.05 to 1.12 V, while maintaining the J sc and fill factor (FF) at 28.2 mA cm −2 and 88.3%, respectively. [ 160 ]…”