In this article, we show that significant performance enhancement can be obtained by incorporating a photo upconverter layer in bulk heterojunction organic solar cells (BHJ OSCs). We systematically optimize the photon upconversion process for P3HT:PCBM, PSBTBT:PCBM, PBDTTT-C:PCBM and PTB7-Th:PCBM based BHJ OSCs using a simple numerical model followed by optoelectronic simulations. After verifying the integrated model of upconversion with experimental reports, we analyze each type of BHJ OSC incorporating photon upconversion layer having optimized spectral characteristics and estimate efficiency enhancement of similar to 30.8% (4.55% -> 5.95%), similar to 24.3% (5.02% -> 6.24%), similar to 28.9% (6.35% -> 8.19%) and similar to 16.9% (10.55% -> 12.34%) for P3HT:PCBM, PSBTBT:PCBM, PBDTTT-C:PCBM and PTB7-Th:PCBM based OSCs, respectively. We then show that effect of photon upconversion and localized surface plasmon resonance on the best performing OSC material considered in this work i.e. PTB7-Th:PCBM, is non-linear and predict a performance boost of mere similar to 2.3% (12.32% -> 12.62%) from additional effort (due to plasmon resonance). Finally, we discuss possibility of extending the efficiency of PTB7-Th:PCBM based BHJ OSC beyond 16% using concentrated sunlight and a practically realizable upconverter layer.